VOLKSWAGEN PASSAT 35I MK3 ABS TEVES MARK 2 BRAKE ANTI LOCK SYSTEM DEVICE.

The ABS TEVES MARK 2  / Teves MK II brake system combines normal system operation, hydraulic power boost and
anti-lock braking. The system uses an independent electrically-driven motor / pump unit to pro-
vide both boost pressure and brake application pressure. A common operating fluid, DOT 4
BRAKE FLUID, is used for both power boost and brake application.

 The BRAKE ANTI LOCK SYSTEM DEVICEIt was originally designed and manufactured by the Brake & Chassis Division of ITT Automotive which was based in White Plains, NY. On September 28, 1998 the division was acquired by Continental AG of Hanover Germany. The name of the newly combined company is Continental Teves AG & Co.

The TEVES Mark II ABS System has been equipped on many different cars of the 80’s Included in the list is the Pontiac 6000 STE and 88-90 Riviera and Reatta. The system also appeared on some SAAB, Mercedes-Benz, Jaguar, Alfa-Romero, and Lincoln Town Cars. Unfortunately for us though, ABS was usually installed as an option, a very expensive one at that so the number of car equipped with "our" system is rather limited when compared to more widely used systems like the TEVES Mark IV which the 93 and up SC’s came standard with. It does open up the chance though that there may be alternatives to FORD to purchasing some replacement parts. It appears though that there are minor differences in the design of each different car’s systems. Substitution should be done only after careful examination and comparison of the parts in question.

The main difference between the TEVES Mark II and Mark IV systems is that the Mark II is an integrated ABS System as opposed to the non-integrated system of the Mark IV. What that means to us is that our system contains all the controlling hydraulic components into one unit called the Hydraulic Actuator Assembly. This includes the Hydraulic Power Booster, master cylinder, pump and motor, valve assembly, and accumulator. On the Mark IV system the ABS system is basically piggy backed onto a conventional brake system to add ABS functionality to it.

Basic TEVES Mark II System Operation

The heart of the TEVES Mark II ABS System is the Hydraulic Actuator Assembly. This assembly is controlled by the Electronic Controller which is mounted in the Package Tray area of the trunk along side the ARC Computer,. Additional vital components include the Four Wheel Sensors and Indicator Rings.

Electronic Controller ATE 535907379 10.0935-0134.4  338540 (STEUER GERAT FUR ABS)

If the Hydraulic Actuation Assembly is the heart of the ABS System the Electronic Controller is the brains. It consists of two parallel microprocessors which operate on the principal of two-channel redundancy for data processing and plausibility criteria monitoring.

The Controller monitors the system operation under normal driving conditions as well as during anti-lock braking. Under normal during conditions the microprocessors send short test pulses to the solenoid valves of the Hydraulic Actuator Assembly that checks the electrical continuity of the system without causing the valves in the Solenoid Valve Block Assembly to change position. When the Electronic Controller senses from the signals that is processes from the four wheel sensors that one or more wheel is about to lock up, signals are sent to the appropriate solenoid valves located in the Solenoid Valve Block Assembly of the Hydraulic Actuator Assembly to allow hydraulic pressure to be bleed away from the wheel(s) that are about to lock. The lock-up condition is sensed when one or more wheels is determined to be decelerating faster than the other wheels. The brake fluid pressure is then reapplied through cycling of the appropriate valves. This occurs at a rate in excess of 10 times a second. The cycling will continue until all wheels are decelerating at approximately the same rate.

  

General Main Relays disposition btw VW PASSAT, Golf, Corrado models
Num.     Relay Arrangement and Pinout (with control number stamped on relay)
1     A/C Relay (13 or 140)
1     A/C Switch
2     Radiator Cooling Fan
3     Fan Switch High Speed
4     Battery, Fuse 23
5     A/C Clutch (via pressure and temperature switches)
6     Main Fusebox Battery Power, Fuse 19
7     Main Fusebox Ground
8     Fresh Air Fan
2     Rear Wiper Relay (72)
1     Main Fusebox Ground
2     Main Fusebox Run Power, Fuse 4
3     Rear Wiper Motor
4     Wipe/Wash Signal from Switch
3     Digifant Control Unit (30 or 32), Motronic OBD1 Control Unit (109)
1     Main Fusebox Ground
2     Tachometer
3     Main Fusebox Start/Run Power
4     Main Fusebox Battery Power
5     To ECU (relay turn-on) (1990 G60, ABA/VR6 OBD1 only)
6     To ECU and Engine Electronics
4     Load Reduction Relay (18)
1     From Ignition Switch Run Power
2     To Main Fuse Box Run Power
3     Main Fusebox Battery Power
4     Main Fusebox Ground
5     Low Coolant Level Control Unit (43)
1     Main Fusebox Start/Run Power
2     Low Coolant Level Sensor
3     Coolant Temperature Sensor, Gauge
4     Main Fusebox Ground
6     Flashers (21)
1     Main Fusebox Ground
2     Flasher Output
3     Flasher Input/Power
4     X/6 (Trailer Light)
7     Headlight Washer (33)
1     Main Fusebox Ground (B/4 to C/3 to Ground)
2     Headlight Washer Pump
3     Headlight Switch Pin 56 (headlights) (B3 to D4 to light power)
4     Main Fusebox Battery Power (B/5 to Y/2)
5     Windshield Washer Pump (B/1 to B/2 to washer pump power)
8     Wash/Wipe/Intermittent Relay (19 for standard relay, 99 for variable intermittent module)
1     Main Fusebox Ground
2     Intermittent Switch
3     Main Fusebox Run Power, Fuse 5
4     Park/Low Signal (ground when parked, positive when on low speed)
5     Wiper Motor Low Speed Output
6     Wash Switch (positive for front wash)
9     Seat Belt Warning Control Unit (4 or 29)
1     Main Fusebox Ground
2     Seat Belt Switch
3     Door Switch
4     Seatbelt Light
5     "Key In" Power from Ignition Switch
6     Main Fusebox Start/Run Power
7     Automatic Shoulder Belt Controller
9     Radio/Lights Buzzer (36)
1     Main Fusebox Ground (not used)
2     A1/4 (Left Parking Lights)
3     Vehicle Speed Sensor
4     Seatbelt Light (not used)
5     "Key In" Power from Ignition Switch
6     Main Fusebox Start/Run Power (not used)
7     A2/2 (Right Parking Lights)
10     Fog Light Relay (110 for fog lights with low beam headlights only, 53 for parking light/high beam fog lights)
1     Parking Light Power
2     Headlight Switch Headlight Power (Low/High)
3     Fog Light Switch Power, Fuse 10
4     Main Fusebox Battery Power
5     Main Fusebox Ground
6     Low Beam Headlight Power
11     Horn (53)
1     Main Fusebox Start/Run Power
2     To Horns
3     Main Fusebox Ground
4     From Horn Button
12     Fuel Pump Relay (80, 67 or 167)
1     Main Fusebox Starter Power (not used)
2     Main Fusebox Start/Run Power
3     To ECU (Fuel Pump Turn-On)
4     To Fuse 18, Fuel Pump, Oxygen Sensor Heater
5     G2/6 (not used)
6     Main Fusebox Battery Power From 30B
7     G2/7, T1 (not used)
8     Main Fusebox Ground (not used)
9     M/4, U1/8, G2/5 (not used)
12     Glow Plug Relay (102 or 104)
1     Main Fusebox Starter Power
2     Main Fusebox Start/Run Power
3     Engine Temp Sender (preheat)
4     Glow Plugs (Z1)To Fuse 18 (not used)
5     G2/6 (not used)
6     Main Fusebox Battery Power From 30B
7     G2/7, T1 (not used)
8     Main Fusebox Ground
9     Water Separator, Glow Plug Light
--------------------------------------------------------------------------------------

 MCS@51 8-BIT CONTROL-ORIENTED MICROCONTROLLERS 8052AH:

 The MCS@51 controllers are optimized for control applications. Byte-processing and numerical operations on
small data structures are facilitated by a variety of fast addressing modes for accessing the internal RAM. The
instruction set provides a convenient menu of 8-bit arithmetic instructions, including multiply and divide instruc-
tions. Extensive on-chip support is provided for one-bit variables as a separate data type, allowing direct bit
manipulation and testing in control and logic systems that require Boolean processing.
The 8751H is an EPROMversion of the 8051AH. It has 4 Kbytes of electrically programmable ROM which can
be erased with ultraviolet light. His fully compatible with the 8051AH but incorporates one additional feature: a
Program Memory Security bit that can be used to protect the EPROM against unauthorized readout. The
8751H-8 is identical to the 8751H but only operates up to 8 MHz.
The 8051AHP is identical to the 8051AH with the exception of the Protection Feature. To incorporate this
Protection Feature, program verification has been disabled and external memory accesses have been limited
to 4K.
The 8052AH is an enhanced version of the 8051AH. It is backwards compatible with the 8051AH and is
fabricated with HMOS IItechnology. The 8052AH enhancements are listed in the table below. Also refer to this
table for the ROM, ROMless and-EPROM versions of each product.

ATE 535907379 10.0935-0134.4  338540 (STEUER GERAT FUR ABS) Circuit configuration for an anti-lock-controlled brake system:VOLKSWAGEN PASSAT 35I MK3  ABS TEVES MARK 2

 This is a circuit configuration provided for an anti-lock-controlled brake system and serving for processing sensor signals obtained by wheel sensors (5) and for generating braking pressure control signals. This circuit configuration contains two microcontrollers (1, 2) interconnected by data exchange lines (7). The handled signals are concurrently processed by the microcontrollers independently of one another and the exchanged signals are checked for consistency. A deviation of the exchanged signals which is due to malfunctions is signalized to a safety circuit (8) which, thereupon, interrupts the power supply to the solenoid valves (Ll . . . Ln). The monitoring signal (WD1, WD2) fed to the safety circuit (8) is a predetermined alternating signal in case of consistency of the exchanged signals and in case of proper operation of the circuit configuration. The safety circuit (8) compares the alternating signal with a time standard derived from a clock generator (TG2, TG3) which is independent of the operating cycle (TG1) of the microcontrollers (1,2). A change in the alternating signal, as well as a failure in the time standard, causes a cut-off of power supply and, hence, of anti-lock control.

1. A circuit for controlling a vehicle anti-lock system operative to receive wheel condition signals from a plurality of wheel condition sensors and generate brake pressure signals in response thereto to modulate vehicle brake line solenoid valves, said circuit comprising:

first microcontroller means and second microcontroller means interconnected by data exchange lines.

(a) said first microcontroller means for:

(1) receiving selected ones of said wheel condition signals,

(2) independently processing said wheel condition signals received by said first microcontroller means,

(3) generating said brake pressure signals in response to said wheel condition signals received by said first microcontroller means,

(b) said second microcontroller means for:

(1) receiving selected ones of said wheel condition signals,

(2) independently processing said wheel condition signals received by said second microcontroller means,

(3) generating said brake pressure signals in response to said wheel condition signals received by said second microcontroller means,

(c) said first microcontroller means also for:

(1) receiving from said second microcontroller means at least one of: PA4 (i) said selected wheel condition signals received by said second microcontroller means, and PA4 (ii) said brake pressure signals generated by said second microcontroller means, and

(2) comparing signals received from said second microcontroller means with corresponding signals received and generated by said first microcontroller means, and

(3) generating a first monitoring signal as a function of any difference between compared signals, said first monitoring signal being an alternating signal having a predetermined frequency and amplitude whenever the difference between compared signals falls below a predetermined threshold level, and

(d) said second microcontroller means also for:

(1) receiving from said first microcontroller means at least one of: PA4 (i) said selected wheel condition signals received by said first microcontroller means, and PA4 (ii) said brake pressure signals generated by said first microcontroller means, and

(2) comparing signals received from said first microcontroller means with corresponding signals received and generated by said second microcontroller means, and

(3) generating a second monitoring signal as a function of any difference between compared signals, said second monitoring signal being an alternating signal having a predetermined frequency and amplitude whenever the difference between compared signals falls below a predetermined threshold level, and

and safety circuit means for:

(a) comparing each of said first and said second monitoring signals with a time standard from at least one clock generator operating independently of an operating cycle of said first microcontroller means and said second microcontroller means, and

(b) disabling said solenoid valves whenever any of said first and said second monitoring signals exceeds said predetermined threshold level.

2. A circuit according to claim 1 further including a trigger circuit through which said wheel condition signals are conducted to said first and said second microcontroller means and containing a first clock generator for said first monitoring signal operating independently of an operating cycle of said first microcontroller means and a second clock generator for said second monitoring signal operating independently of an operating cycle of said second microcontroller means.

3. A circuit according to claim 2 further including:

(a) a power supply,

(b) means for selectively conducting power from said power supply to said solenoid valves to actuate said solenoid valves, and

(c) valve control means responsive to said safety circuit means for preventing actuation of said solenoid valves.

4. A circuit according to claim 3 further including second valve control means responsive to said safety circuit means for preventing actuation of said solenoid valves.

5. A circuit according to claim 4 further including amplifying means between said first and said second microcontroller means and said solenoid valves, and said second valve control means control said amplifying means.

6. A circuit according to claim 5 further including monitoring circuit means for:

(a) developing control signals representative of defects in said anti-lock system, and

(b) supplying said control signals to said first and said second microcontroller means

and wherein said first and said second monitoring signals indicate the presence of said control signals.

7. A circuit according to claim 6 wherein said monitoring circuit means include a parity chain responsive to operation of said solenoid valves and said brake pressure control signals.

8. A circuit according to claim 1 wherein each of said first and said second monitoring signals is compared with a separate time standard from a separate clock generator operating independently of an operating cycle of said first microcontroller means and an operating cycle of said second microcontroller means.

9. A circuit for controlling a vehicle anti-lock system operative to receive wheel condition signals from a plurality of wheel condition sensors and generate brake pressure signals in response thereto to modulate vehicle brake line solenoid valves, said circuit comprising:

signal processing circuit means for:

(a) receiving said wheel condition signals, and

(b) generating said brake pressure signals in response to said wheel condition signals,

said signal processing circuit means including:

(a) first microcontroller means for:

(1) receiving selected ones of said wheel condition signals,

(2) independently processing said wheel condition signals received by said first microcontroller means, and

(3) generating said brake pressure signals in response to said wheel condition signals received by said first microcontroller means, and

(b) second microcontroller means for:

(1) receiving selected ones of said wheel condition signals,

(2) independently processing said wheel condition signals received by said second microcontroller means, and

(3) generating said brake pressure signals in response to said wheel condition signals received by said second microcontroller means, and

(c) data exchange means interconnecting said first and said second microcontroller means for exchanging between said first and said second microcontroller means at least one of:

(1) said selected wheel condition signals, received by said first and said second microcontroller means, and

(2) said brake pressure signals generated by said first and said second microcontroller means, and

(d) said first microcontroller means also for:

(1) comparing signals received from said second microcontroller means with corresponding signals received and generated by said first microcontroller means, and

(2) generating a first monitoring signal as a function of any difference between compared signals, said first monitoring signal being an alternating signal having a predetermined frequency and amplitude whenever the difference between compared signals falls below a predetermined threshold level,

(e) said second microcontroller means also for:

(1) comparing signals received from said first microcontroller means with corresponding signals received and generated by said second microcontroller means, and

(2) generating a second monitoring signal as a function of any difference between compared signals, said second monitoring signal being an alternating signal having a predetermined frequency and amplitude whenever the difference between compared signals falls below a predetermined threshold level,

and safety circuit means, including at least one clock generator operating independently of an operating cycle of said first microcontroller means and an operating cycle of said second microcontroller means, for:

(a) comparing each of said first and said second monitoring signals with a time standard from said clock generator, and

(b) disabling said solenoid valves whenever any of said first and said second monitoring signals exceeds said predetermined threshold level.

10. A circuit according to claim 9 wherein said safety circuit means include two clock generators each operating independently of an operating cycle of said first microcontroller means and an operating cycle of said second microcontroller means and said first monitoring signal is compared with a first time standard from said first clock generator and said second monitoring signal is compared with a second time standard from said second clock generator. 

Description:

INTRODUCTION
This invention relates to a circuit configuration for an anti-lock-controlled brake system, which circuit configuration serves for processing sensor signals that have been obtained by means of wheel sensors and that represent the rotational behavior of the vehicle wheels and for generating braking pressure control signals by means of which solenoid valves inserted into the brake lines can be changed over, and which circuit configuration is provided with two or more microcontrollers that are interconnected by data exchange lines and can be fed with the sensor signals after the same have been handled in a trigger circuit, with the microcontrollers independently of one another processing the sensor signals, generating the braking pressure control signals, checking the exchanged signals for consistency and feeding a monitoring signal to a safety circuit which interrupts the power supply to the solenoid valves in case of malfunctions. 

BACKGROUND OF THE INVENTION
Such a circuit configuration has come to knowledge from German Published Patent Application (DE-OS) No. 3234637. The handled signals of all wheel sensors are fed concurrently to two electronic circuits and are there processed by means of identical logic or rather in accordance with identical programs for the purpose of identifying malfunctions of the electronic circuitry. The signals available at different points in the course of the program are exchanged and checked for consistency. Any deviations are an indication of malfunctions wherefore in such a case either of the two electronic circuits signalizes this malfunction to one or several safety circuits. This causes a cut-off of the power supply to the solenoid valves serving for anti-lock control. As, in their rest positions, the solenoid valves do not influence the pressure medium supply to the brake and, hence, the brake application, nor permit any pressure removal via the outlet valves it is ensured that the vehicle will continue to be able to be braked, although without anti-lock control, in case of a trouble in the electronic system. 

BRIEF DESCRIPTION OF THE INVENTION
However, in such a circuitry it is conceivable, although unlikely, that there are cases where anti-lock control will remain switched on despite a malfunction. Therefore, it is an object of the present invention to enhance the degree of safety even more, with which anti-lock control will be switched off in case of a trouble in the electronic or electric system, and thus to increase the safety of maintaining the braking operation, although without control. This object ought to be achieved without any additional expense or with very little additional expense at the maximum.
It has been found out that this object can be solved in a circuit configuration of the type referred to at the beginning in that, in case of consistency of the exchanged signals and in case of proper operation of the circuitry, the monitoring signal of each microcontroller is a predetermined alternating signal, i.e., an alternating signal with predetermined frequency and with predetermined variation; and in that the safety circuit compares the monitoring signal, or rather the alternating signal, with a time standard derived from one or several clock generators which are independent of the operating cycle of the microcontrollers.
According to this invention, the enhanced safety will thus be achieved in that an alternating is selected as monitoring signal by means of which each microcontroller signalized the proper condition to the safety circuit; and in that this alternating signal is compared with a time standard. The alternating signal, for instance, is a pulse sequence of predetermined duration and frequency. Moreover, a time standard, or rather a time window, is used for the monitoring signal of each microcontroller. Said time standard, or rather time window, is gained independently of the operating cycle of the microcontrollers by means of additional clock generators. These clock generators may be of simple construction as they only have to check relatively roughly whether the monitoring signal falls into the predetermined time window. Such clock generators, for instance, permit integration at low expense into the trigger circuit provided for the wheel sensor signals.
Should there be a failure of the clock generators defining the time windows this would also lead to a cut-off of anti-lock control. Thus the monitoring assemblies are also included in the monitoring operation.
According to one advantageous embodiment of this invention, the monitoring signal of each microcontroller is compared with the time window derived from a specific clock generator. As compared with the use of a common clock generator this will once more enhance the safety degree of error detection.
It will be an advantage if, upon error detection, the safety circuit interrupts the power supply path of a relay via the operating contact of which power supply to the solenoid valves takes place. A very expedient embodiment of such a circuit configuration for actuating the power supply relay is described in the German Patent Application No. P 39 24 988.3. If such a circuit configuration is used it will be ensured that power supply will be interrupted even in case of troubles of various types within the relay actuation system.

A further very advantageous embodiment of this invention consists in that, upon error detection, the safety circuit actuates semiconductor stages such as transistor stages via an additional signal output which block the actuation of the solenoid valves, e.g., by interrupting power supply to the driver stages, or rather amplifier stages, connected upstream of the solenoid valves. In this way, any further anti-lock control will be prevented even if the detected trouble admittedly will cause the safety circuit to respond, with the supply voltage, however, not being switched off because of a bridged switching contact, for instance.
According to a further embodiment of this invention, the microcontrollers will not only signalize defective operation if the mutually exchanged signals are not consistent but also if there appear signals or signal combinations which will not be possible in case of proper operation of the anti-lock control system. Monitoring thus also takes place in accordance with so-called plausibility criteria.
According to another favorable example of an embodiment of this invention, the output signal of a monitoring circuit is feedable to the microcontrollers, the error detection state of said output signal--e.g., a permanent signal instead of an alternating signal--being signalizable as malfunction to the safety circuit by means of the microcontrollers and of the monitoring signals. The output signal, for instance, may be an output signal of a parity chain monitoring the operation of the solenoid valves. A very advanced monitoring circuit of this type is described in German Patent Application No. P39 25 418.8.
Further characteristics, advantages and applications of this invention will become evident from the following description of one example of an embodiment, reference being made to the accompanying drawing. 

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1, is a block diagram showing the essential components of a circuit configuration in accordance with this invention; and
FIG. 2, shows details of one component of the circuit configuration as per FIG. 1. 

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In accordance with FIG. 1, the essential components of a circuit configuration for an anti-lock-controlled brake system are two microcontrollers 1,2 (MC1 and MC2) which, via signal lines 3, 4, are fed with the information on the rotational behavior of the individual vehicle wheels and which generate braking pressure control signals after these signals have been logically linked and handled.
The wheel information are obtained in the known manner by means of wheel sensors 5 whose signals are processed in a trigger circuit 6 and, subsequently, are passed on to the microcontrollers 1, 2. In the illustrated example of an embodiment, via lines 3 and 4, respectively, each microcontroller is fed the information of two wheel sensors out of the four wheel sensors; however, via the data exchange lines 7, the wheel information are also exchanged so that, independently of each other, in both microcontrollers it will be possible to derive braking pressure control signals from the input information, with the same program being used.
The output signals of the microcontrollers 1, 2 serve as braking pressure control signals. After amplification in valve drivers VT1, VT2 . . . VTn, said output signals will be fed to power transistors LT1, LT2, . . . LTn which directly actuate solenoid valves. The excitation coils of the solenoid valves are referred to by L1, L2 . . . Ln. The (non-illustrated) solenoid valves serve for braking pressure modulation within the scope of anti-lock control. In the rest position said solenoid valves do not have any influence on the braking operations.
The braking pressure control signals are likewise generated independently of one another in both microcontrollers 1, 2, and are compared via data exchange lines 7. In the illustrated example of an embodiment, the connections to the individual solenoid valves are distributed to the two microcontrollers 1, 2 because of the limited number of the available outputs, or rather connection pins.
Monitoring lines WD1, WD2 lead from the microcontrollers 1, 2 to a safety circuit 8. Via outputs of said safety circuit 8, two power transistors LT3, LT4 are actuated that are connected in series and via which a power supply relay, or rather a main relay 9, is energized which, via an operating contact 10, maintains the power supply to the solenoid valve and their actuation circuits (VT1 . . . VTn). A circuit 11 serves for the voltage supply UB of the safety circuit 8 and for triggering a reset pulse.
A further output of the safety circuit 8 leads to two cascade-connected transistors 12, 13. In case of proper operation, transistor 13 is conductive and supplies the valve drivers VT1, VT2 . . . VTn as well as the power transistors LT1, LT2 . . . LTn with energy. Power supply to the valve drivers and power transistors will be blocked via transistor 13 if transistor 12 is actuated by safety circuit 8.
A monitoring circuit 14 to be explained in more detail in the following with reference to FIG. 2 supplies a signal to the two microcontrollers 1, 2 via a line 15. In a certain way, said signal will be dependent on the correction signals of the microcontrollers 1, 2, or rather on the actuation of the solenoid valves L1 . . . Ln, as long as the monitored elements and windings L1, L2 . . . Ln are in good order. If a trouble comes up the signal at output A will deviate from the "expected" signal.
A clock generator TG1 is provided for the generation of an operating cycle for the microcontrollers 1, 2, its clock frequency being determined by a quartz. The operating cycle of the microcontrollers 1, 2 also determines the frequency and the shape of the monitoring signals WD1, WD2 that signalize intact condition and proper operation to the safety circuit. In one example of an embodiment of this invention, the monitoring signals WD1, WD have the shape of short pulses of a duration of 200/us which are repeated every 7 ms.
Two further clock generators TG2, TG3 which are independent of clock generator TG1 are provided for the generation of time windows or time standards by means of which the monitoring signals are comparable. In the present example, said clock generators TG2, TG3 are integrated into the trigger circuit 6.
Monitoring of the circuit configuration as per FIG. 1 will be performed as follows:
The two microcontrollers 1, 2 contain circuits that permanently perform a consistency check of the signals exchanged via the data exchange lines 7. Moreover, in a manner known per se, it is established within the circuits 1, 2 whether predetermined plausibility criteria are complied with, or rather whether the signals formed within the scope of signal processing will be possible in case of intact circuitry and proper operation. Finally, it is also checked whether an alternating signal is actually available at output A of the monitoring circuit 14, or rather at the corresponding inputs which are given access to by line 15. If all these conditions are complied with independently of one another in either of the microcontrollers 1, 2 this will be signalized to the safety circuit 8 by means of the monitoring signals WD1, WD2 which, in this case, represent an alternating signal of a certain shape and frequency such as a pulse sequence of a certain frequency.
The two monitoring signals WD1, WD2 are compared independently of each other with corresponding time standards derived from the clock generators TG2, TG3. As long as there is no deviation indicating a trouble or a malfunction the power transistor LT3, LT4 connected to the corresponding outputs of the safety circuit 8 can be activated, the relay 9 remaining switched on. The voltage UB is applied to the illustrated circuit and to the solenoid valves. There is no signal at the third output of the safety circuit 8, which leads to transistor 12, so that also the valve drivers and the power transistors are connected to the battery voltage UB via transistor 13.
If now there occurs a malfunction detected by the monitoring circuit 14 and/or by the microcontroller 1 and/or 2 this will lead to a corresponding change in the monitoring signal WD1 and/or WD2. The safety circuit 8 will react by ending actuation of transistors LT3, LT4, thereby causing relay 9 to drop out and interrupting the power supply to the entire circuitry. Additionally, the power supply to valve drivers VT1 . . . VTn and to power transistors LT1 . . . Ltn will be blocked in the described way via the third output of the safety circuit 8. This, however, will only be of importance if cut-off via relay 9 does not work or is delayed.
A corresponding reaction of safety circuit 8 will also come about if one or both monitoring signals WD1, WD2 are no longer consistent with the time standards derived from the clock generators TG2, TG3 or if either clock generator TG2, TG3 becomes defective, with the monitoring signals WD1, WD2 being intact. Consequently, the monitoring elements themselves are monitored . 

FIG. 2, referring to an example of an embodiment with four solenoid valves whose excitation windings are referred to by L1-L4, serves to explain the connection and mode of operation of the monitoring circuit 14 of FIG. 1. This circuit is described in detail in Patent Application No. P 39 25 418.8 mentioned at the beginning.
The signal at output A, or rather on line 15, is dependent on the signal variation, or rather on the signal distribution, at all the outputs of the microcontrollers 1, 2 that are connected via the monitoring circuit 14. For instance, a change in the signal level at any one of the outputs of the microcontrollers 1, 2 with the levels at the remaining outputs staying the same, automatically will cause a change in level on line 15. In the microcontrollers 1, 2 it will always be checked whether the signal at the output of monitoring circuit 14 will be in conformity with the signal distribution at the outputs of the microcontrollers 1, 2.
The transistors T1-T4 of the monitoring circuit 14, together with the remaining components combined in circuit block 16, form an OR-link whose output signal is formed by means of transistors T5, T6 and is available at an output A1. Connected at the base of transistor T5 are a current source Q1 towards the ground and an ohmic resistor R1 towards the supply voltage UB. The emitter of transistor T5 is connected with the battery UB via a low-impedance resistor R2. The current source Q1, the base resistor R1 and the emitter resistor R2 are dimensioned such as to ensure that, as long as the transistors T1-T4 are non-conductive, the two transistors T5 and T6 will carry a current so that there will prevail the signal state L (low) at output A1.
There will be a change in the level at output A1 if at least one valve is excited, or rather if one of transistors LT1 . . . LTn is actuated (in FIG.2 only LT1 and the appertaining driver stage VT1 are sketched out).
As long as the power transistors are not actuated the transistors T1-T4 will be non-conductive as each transistor base, which in each case is connected to the battery voltage UB via one of the low-impedance windings L1-L4, is on the potential of the voltage source UB. The current flowing via R2 and the transistors T5, T6 will cause a drop in voltage in the blocking direction of the base-emitter diode of transistors T1-T4.
The base connections of transistors T1-T4 are connected to one output A2 by means of non-equivalent elements XOR1, XOR2, XOR3 (exclusive OR). Each of said non-equivalent elements has two inputs and one output and they are combined into a so-called parity chain in that in each case a control connection of a valve excitation winding is linked with the output a signal of a non-equivalent element. In the illustrated manner, it is possible to connect any number of solenoid valves, or rather of valve excitation windings, to one output A.
The OR-link 16 also reacts to leakage currents via the windings L1-L4. As the drop in voltage on the low-impedance resistor R2 is small, a relatively small leakage current flowing via any one of the windings will already cause the corresponding transistor T1-T4 to become current-carrying, thereby the drop in voltage on R2 being increased that much as to cause T5 and, hence, also T6 to become non-conductive. This again is detectable by means of a signal change at output A1 of the OR-link and, thus, at output A of the monitoring circuit, also.
Consequently, a certain signal variation at the output of the monitoring circuit 14 will correspond to the signal variation at the power transistors LT1, LT2 through LTn, or rather at the outputs of the microcontrollers 1, 2 (FIG. 1). The defect of any power transistor LT1 . . . LTn, an excessive saturation voltage, a short circuit or the like are consequently detectable by means of the monitoring circuit 14.

Hydraulic Actuator Assembly (Figure 1)

The Hydraulic Actuator Assembly is made up of several sub components. These include:

1. The Hydraulic Actuation Assembly
2. Electric Pump and Accumulator Assembly
3. Solenoid Valve Block Assembly
4. Brake Fluid Reservoir and Level Indicator Assembly

Each of these sub components provides essential functions to the assembly as a whole. The system is a 3 channel system meaning that brake fluid can be controlled to each of the two front wheels independently and to the rear wheels as a unit.

1. The Hydraulic Actuation Assembly 

This assembly consists of two sections. The master cylinder and brake booster. These are arranged in two parallel bores with the master cylinder being below the brake booster. The brake booster contains a main control valve which is operated by a lever connected to brake pedal rod. During normal braking when the brake pedal is pushed, this lever causes the control valve to modulate the amount of pressurized brake fluid applied to the rear brakes via a proportioning valve. The control valve also ports brake fluid to the master cylinder pistons which applies braking pressure to the front brakes. The source of this pressurized brake fluid is the accumulator which will be detailed later. Also the fluid must pass through normally open Load Solenoid valves in the Solenoid Valve Block Assembly. The operation of this assembly will be detailed later as well.

 

 

• During the Anti-lock braking mode, the main control valve actuates allowing pressurized brake fluid to enter a chamber behind the master cylinder pistons and into the front brake circuits through the appropriate solenoid valves as required. The pressurized brake fluid also exerts force against a reaction sleeve which raises the brake pedal. This allows a 70% stroke of the front brake master cylinder pistons in the unlikely event of an anti-lock malfunction. The Actuation Assembly, Master Cylinder, booster and main valve are serviced as an assembly.

2. Electric Pump and Hydraulic Accumulator Assembly (Figure 2)

The ABS System uses stored high pressure brake fluid as a source for power assist as well as for the rear brake circuit. The Pump is controlled primarily by the attached pressure switch which senses Hydraulic Accumulator pressure. The Accumulator is a Gas filled reservoir which contains a flexible diaphragm. When the pump runs, it forces brake fluid into the accumulator where it presses up again the diaphragm. This pressurization continues until pressure reaches approximately 2650 PSI. At this point the pressure switch opens allowing the Hydraulic Pump Motor Relay to drop out causing the pump to stop. The pump motor is protected by an internal thermal switch. If the motor overheats due to prolonged running (20 minutes continuous or so) the thermal switch will open shutting off the motor for 2-10 minutes until it cools down. The electrical operation of the system will be detailed later. The Accumulator and Pressure Switch are serviced separately while the pump and motor is serviced as a unit.

 3). Solenoid Valve Block Assembly

This assembly houses three pairs of solenoid valve , one for each of the three channels of the ABS System. The pairs of valves are inlet/outlet valves which I will call Load and Dump Valves. In normal operation the Load valves are open and the Dump valves closed. This allows pressurized brake fluid to be properly ported to the appropriate front brake circuits via the Master Cylinder and Main Control Valve and the rear circuit via the proportioning valve. During a Anti-lock condition the circuit for which a wheel is sensed to be in a potential lock-up condition the inlet valve will shut and the dump valve will open. This reduces the amount of pressure felt at the wheel for the brake caliper thus reducing clamping pressure of the brake pads on the brake rotor. The valves will cycle to Inlet open Dump shut restoring brake pressure. This cycling will occur up to 10 times per second until the Electronic Controller senses that "normal" braking has been restored. The Solenoid Valve Block Assembly is serviced as a separate unit.

4. Brake Fluid Reservoir and Level Indicator Assembly

• The Brake Fluid Reservoir and Fluid Level Indicator (FLI) Assembly is a translucent, plastic container that is mounted on top of the Hydraulic Actuation Assembly. The reservoir is connected to the pump inlet by a low pressure hose, and to the master cylinder by a sealed feed port. The FLI provides a warning signal visa the red Brake Light should the brake fluid level fall below the proscribed minimum. If level continue to lower this will cause the Amber Anti-Lock warning light to illuminate as well. Additionally the Electronic Controller will stop the ABS System from operating. The reservoir and FLI are serviced as a unit.

VW PASSAT MK3 ABS Wheel Sensor and Indicator Rings:

The ABS Unit uses four sets of variable reluctance sensor and toothed speed indicator rings. These two devices work together to determine the rotational speed of each wheel. The work under a magnetic induction principle. As the teeth on the indicator rings rotate past the stationary sensor a signal proportional to the rotational speed of the wheel is generated. This voltage is an analog AC signal which is fed to the Electronic Controller via coaxial cables, one for each sensor. The frequency of the signal is dependent on how fast the toothed indicator ring is passing by the stationary sensor. It is the frequency that is used to determine wheel speed by the Electronic Controller. On the front wheels the toothed indicator rings are mounted on the back side of the Hub Assembly. On the rear they are mounted as part of the inner CV Joint assembly. The front sensors are attached to the front spindle and on the rear to the axle housing. The indicator rings and speed sensors are serviced separately. A fine point to be aware of though is that only the correct speed sensor can be installed at each wheel location. If you decide to get replacements from the junkyard, make sure you mark the sensors front to back and left to right and only install the sensor at it’s proper point in the system.

 

 Electrical Operation of the ABS System: ABS TEVES MARK 2:

 When the ignition key is placed into the start or run position, power is applied to a portion of the ABS Control Module (Electronic Controller) via the 10A CLUSTER Fuse. The ABS Control Module applies power to the Anti-Lock Power Relay when the Ignition Switch is placed into the START Position. This relay closes it’s contacts allowing power to flow from the ABS MOD 30A Fuse in the Primary Distribution Box (inside the engine compartment) to the rest of the ABS Control Module. This relay is a "seal-in relay" in that it continues to be closed even when the Ignition Switch is released to the run position. The purpose for this relay is that it allows a relatively large amperage load to be powered but not directly from the ignition switch. This way up to 30A of power can be supplied to the system without relying on the contacts in the ignition switch to do it. After the system is energized it performs a self test. If you place your ignition switch to the run position without starting the car you can watch this test being run. This self test will check electrical continuity of the system as well as the Electronic Controller for proper operation. The Amber Anti-Lock light will illuminate for approximately 4 seconds and then extinguish if all is well with your system. If you then place the switch to the start position and start your car you should see the following cycling of lights. The Amber Anti-Lock and Red Brake Light should illuminate. The Hydraulic Pump Motor most likely will run since the pressure sensed by the Pressure Switch in the system is probably low (below 2030 PSI)if the car has been sitting a while. The Pressure Switch will allow power from the ANTI LOCK 10A Fuse to cause the Hydraulic Pump Motor Relay to close it’s contacts allowing power to flow to the pump motor from the ABS MTR 40 A fuse. It will also cause the Anti-Lock Warning Light to be illuminated. The pump running will pressurize the hydraulic accumulator to around 2650 PSI at which point the pressure switch contacts will open, the Hydraulic Pump Motor Relay will drop out and the pump will stop as well as the red and amber lights will extinguish.

VOLKSWAGEN PASSAT 35I MK3  ABS TEVES MARK 2 Basic Troubleshooting:

Most of the problems associated with this system seem to revolve around the electrical operation of the Hydraulic Pump Motor and the Accumulator. So lets describe what some of the common symptoms are and what you can do about it.

Hard pedal Amber Anti Lock and Red Brake Light always on.

• The hard pedal is indication of no power assist which we now knows means the Accumulator is not pressurized or the hydraulic pump is not running to pressurize the system. You should also realize that you don’t have ANY rear brakes too. Run the Self Test and see the Amber Warning Light goes out in 4 seconds. Have an assistant stand by the open hood to listen for the Hydraulic Pump Motor to run when you start the car.
• If the pump runs, most likely you have a bad Accumulator or the pump is not being supplied with fluid because sediment has plugged the low pressure hose leading from the reservoir. Check the hose is unplugged and if that doesn’t correct the problem replace the Accumulator. If this doesn’t fix your problem you are into a high buck Pump Assembly replacement. (You already replaced the Accumulator so don’t buy another one now). For reference you should be able to press on the brake pedal from 5-8 times without the Hydraulic Pump Motor running. If this is not that case you are due for an Accumulator soon.

If the pump does not run you now most likely have an external electrical problem although it is possible the pump motor is shot. Here is how to tell what is what. With the Ignition Switch off depress the brake pedal 20 times to ensure the system is fully depressurized. Turn the Ignition Switch to Run the pump should run. If not disconnect the 4 pin connector on the pump. Use a multi meter to measure the voltage on the pins of the harness connector. The two positive pins are on opposite side of the connector as are the negative pins. Measure from one positive to one negative pin. .You should measure more than `10V DC. If you don’t, potential problems include either the Hydraulic Pump Motor Relay, The Pressure Switch or the wiring harness between them all.

The failure of the Hydraulic Pump Motor Relay is a common occurrence. The normal failure modes are the contacts welded themselves shut causing the Hydraulic Pump Motor to run continuous or the relay failing to close which prevents normal pump motor operation.

Anti-Lock Warning Light and Red Brake Light come on after brakes applied.

• Most likely this is indication of a weak or bad Accumulator. If you have this symptom it is important to fix it as soon as you can because you are cycling the Hydraulic Pump Motor unnecessarily which will cause this high buck part to fail sooner than it needs to.

Red Brake Light comes on when accelerating or braking or going around a corner hard.

• Probably your brake fluid level is a tad low. Angles and dangles on the car are causing it to pick up the level sensor. Make sure your system is pressurized when you check / add fluid since the Accumulator will "store" an appreciable amount of fluid. This will cause the level to go down as the system is pressurized at start up. Where did the fluid go you might ask? Assuming you have no leaks it probably is as a result of the brake pads in your calipers wearing. As they wear more fluid is required to keep the caliper pistons maintained in the proper position for braking action. 

SPECIAL FEATURES
These instructions, valid at the time of publication, contain trouble-shooting
procedures Teves ABS Mark II for the following models:
VW Corrado 10.88 , PASSAT ->
ABS with 4 wheel-speed sensors and 3-channel hydraulic modulator featuring
7 solenoid valves.
The ABS control unit is equipped with self-diagnosis with 4-position flashing
code.
The fault memory is not cleared after switching off the ignition.
All faults occurring are stored and divided into 7 priority classes. The
controller is then completely or partially deactivated depending on priority
class.
The ABS system is fully deactivated in the event of priority 1 faults (for
example: solenoid valve defective).
A 35-pole plug is located at the controller.
Sensor ring gears with 43 teeth each.
The high-pressure pump motor may run continuously for a maximum of 2 min;
it should then be allowed to cool down for at least 10 min.
The solenoid valves can be directly actuated for brief periods.
Switch-on time max. 10 s.
ABS function
The main solenoid valve is always active with ABS controlled braking. It
switches the accumulator pressure directly to the inlet and outlet solenoid
valves by way of the collars of the brake master cylinder (collar overflow). In
accordance with the lock-up tendency, pressure holding, pressure reduction or
pressure build-up is implemented at the respective wheel brake cylinders by
way of the inlet and outlet solenoid valves.

1 = High-pressure pump with pressure accumulator and pressure switch
2 = Brake-fluid reservoir
3 = Main solenoid valve
4 = Wheel brake cylinder
5 = Inlet and outlet solenoid valve, front right
6 = Inlet and outlet solenoid valve, front left
7 = Inlet and outlet solenoid valve, rear
8 = 2-circuit brake master cylinder
9 = Hydraulic modulator
10 = Hydraulic brake booster
11 = Load-sensitive braking-force regulator
12 = Brake-pressure control valve
The brake booster is supplied by the pressure accumulator and simultaneously
acts on the rear-wheel brakes by way of a load-sensitive braking-force
regulator. There is no braking effect at the rear axle in the absence of
accumulator pressure.
Attention is therefore to be paid to the bleeding specification when bleeding the
brake system.

Bleeding specification:

Bleeding of the front wheel brakes is implemented normally with a
charging/bleeding unit.
- Attach bleeder bottle, front left and loosen the bleeder screw by one turn.
- Close bleeder screw when brake fluid emerges with no bubbles.
- Repeat procedure for brake cylinder, front right.
- Check brake fluid level.
Rear axle:
- Ignition off.
- Press brake pedal approximately 20 times (to empty high-pressure
accumulator) until there is a noticeable increase in pedal force.
- Attach bleeder bottle, rear left and loosen bleeder screw by one turn.
- Fully depress brake pedal and hold it down with pedal locking device.
- Ignition on, high-pressure pump running (pay attention to running time max.
2 min !).
- Close bleeder screw when brake fluid emerges with no bubbles.
- Check brake fluid level.
- Release brake pedal.
- Wait until high-pressure accumulator is full (high-pressure pump switches
off).
- Ignition off.
- Attach bleeder bottle, rear right and loosen bleeder screw by one turn.
- Press brake pedal slightly.
- Close bleeder screw when brake fluid emerges without bubbles.
- Release brake pedal.
- Ignition on.
- Wait until high-pressure accumulator is full (high-pressure pump switches
off).
- Check brake fluid level.
STRUCTURE, USAGE
These brief instructions essentially comprise vehicle-specific special features
and set values.
There is no detailed description of trouble-shooting in basic instructions.
User prompting is provided on every page e.g.:
- Continue: I 17/1
- Continue: II 18/1 Fig.: II 17/2
- Yes: I 20/1 No: I 19/1
- Yes: I 22/1 No: I 21/1 Fig.: I 20/2
Brief instructions may include several rows of coordinates.
I../. = first coordinate row
II../. = second coordinate row
III../. = third coordinate row etc.
.../1 = upper coordinate half
.../2 = lower coordinate half
SAFETY MEASURES
As regards the hydraulic modulator, safety reasons dictate that only the
compensating tank, pressure accumulator, pressure warning switch, high-
pressure pump and valve block may be replaced. Do not loosen any other
screws on hydraulic modulator! Such a course of action could lead to fatal
brake failure.
Take care when handling brake fluid.
T O X I C!

The ABS is a vehicle safety system.
Work on this system presupposes detailed system knowledge.
Testing may only be performed by trained personnel.
After loosening hydraulic connections, bleed brake system and perform low-
pressure as well as high-pressure test.
Pay attention to special bleeding specification.
For further safety measures, refer to basic instructions of AUDI V8 10.88->
(KFZ-00.)

WARNING LAMP FUNCTION
The ABS warning lamp must go out within 60 s after switching on ignition.
If the ABS warning lamp does not go out after starting or if it lights
(continuously or intermittently) whilst driving, there is a fault present and the
ABS system is completely or partially deactivated depending on the fault
priority.
Intermittent faults (loose contacts) are likewise stored.
The flashing code must therefore always be read out first when performing
trouble-shooting.
The brake warning lamp is designed to give an indication of handbrake on, low
brake-fluid level or inadequate accumulator pressure.

Either the accumulator pressure or the brake-fluid level is too low if both
warning lamps light simultaneously.
If the brake warning lamp lights, the conventional brake system is first to be
checked and repaired if necessary.

SELF-DIAGNOSIS
Flashing code output:
- Lever gear-lever boot off center console.
- Connect KDAW 9975; see picture.
Note: The sequence of connectors (picture) does not have to coincide with that
in the vehicle.
Black plug (A) with bevel at top on both sides is always voltage supply.
Blue/white plug (B) beveled on side at top and bottom is stimulation lead (B/1).
Each flashing code is initiated by way of a start pulse (lamp on) with duration
of approx. 2,5 s. The individual positions are separated in each case by an
interval (lamp off) of approx. 2,5 s.
Only the short flashing pulses are to be counted. The flashing code is
constantly repeated. The next flashing code is not output until the button is
pressed for approx. 3 s.
See picture: flashing code 1234.
Priority 1 faults are output first and halt further flashing-code output. Eliminate
fault and stimulate again.
Note: If the flashing code is not output, determine the correct diagnosis plug
from controller plug term. 26.
- Press button.
- Switch on ignition.
- ABS warning lamp lights.

- Release button after approx. 3 s.
- Flashing code is flashed up by way of ABS warning lamp and constantly
repeated.
- Read out entire fault memory and note down each individual flashing code.
The fault memory has been completely read out when the warning lamp flashes
continuously and uniformly in 2,5 second cycle (flashing code 0000).
A test drive is to be performed after repairing the ABS system. In doing so,
drive for at least 1 minute at a speed in excess of 40 km/h.
Note: Remove all diagnosis leads when performing test drive.

Note:
Fault memory is automatically cancelled during test drive. The only faults to be
cancelled are those, which have previously been read out at least once.

Read out fault memory again. If flashing code 4444 is output, there are no
further faults stored in the ABS controller. If no flashing code is output or the
flashing code is not listed in the table, refer to component/functional test.

Test instructions:
Do not use test prods for measurements at all equipment plugs, but rather make
use of suitable test plugs from Bosch test cable set 1 687 011 208 as otherwise
contacts could be damaged.

SELF-DIAGNOSIS FLASHING CODE TABLE
0000 End of output/controller
END OF OUTPUT/controller
- Remove all diagnosis leads.
- Following repair, perform test drive for at least 1 min. at a speed in excess of
40 km/h.
- Repeat self-diagnosis.
1111 Controller
SELF-DIAGNOSIS FLASHING CODE 1111
Controller
- Check all fuses.
- Ignition off.
- Pull plug off controller.
- Check ground connections at controller plug. X1 term. 1, 11 -> body ground
Set value: < 0,5 Ohm
- Ignition on and start engine.
- Check voltage supply at controller plug. X1 term. 2 -> body ground
Set value: 11...15 V
- Controller defective.
1112 Inlet valve VL
SELF-DIAGNOSIS FLASHING CODE 1112
Inlet valve, front left
- Ignition off.
- Pull plug off controller.
- Check solenoid valve resistance at controller plug. X1 term. 11 -> X1 term.
35
Set value: 5...7 Ohm
- Check solenoid valves and leads for short to ground/short to positive, open
circuit and loose contacts as per circuit diagram.
- Check contacts of connectors.
SELF-DIAGNOSIS FLASHING CODE 1112...1222
- Remove solenoid valve relay.
- Check function of valve relay.
- Check ground connection, valve relay. K1 term. 87a -> body ground Set
value: < 0,5 Ohm
- Check voltage supply, valve relay. K1 term. 87 -> body ground
Set value: 10...15 V
- Check lead from valve relay to controller plug. K1 term. 30 -> X1 term. 3, 20
- Controller defective.
1114 Inlet valve VR
SELF-DIAGNOSIS FLASHING CODE 1114
Inlet valve, front right
- Ignition off.
- Pull plug off controller.
- Check solenoid valve resistance at controller plug.X1 term. 11 -> X1 term. 15
Set value: 5...7 Ohm
- Check solenoid valves and leads for short to ground/short to positive, open
circuit and loose contacts as per circuit diagram.
- Check contacts of connectors.
SELF-DIAGNOSIS FLASHING CODE 1112...1222
- Remove solenoid valve relay.
- Check function of valve relay.
- Check ground connection, valve relay. K1 term. 87a -> body ground
Set value: < 0,5 Ohm
- Check voltage supply, valve relay. K1 term. 87 -> body ground
Set value: 10...15 V
- Check lead from valve relay to controller plug. K1 term. 30 -> X1 term. 3, 20
- Controller defective.
1122 Inlet valve HA
SELF-DIAGNOSIS FLASHING CODE 1122
Inlet valve, rear
- Ignition off.
- Pull plug off controller.
- Check solenoid valve resistance at controller plug. X1 term. 11 -> X1 term.
17
Set value: 5...7 Ohm
- Check solenoid valves and leads for short to ground/short to positive, open
circuit and loose contacts as per circuit diagram.
- Check contacts of connectors.
SELF-DIAGNOSIS FLASHING CODE 1112...1222
- Remove solenoid valve relay.
- Check function of valve relay.
- Check ground connection, valve relay. K1 term. 87a -> body ground
Set value: < 0,5 Ohm
- Check voltage supply, valve relay. K1 term. 87 -> body ground
Set value: 10...15 V
- Check lead from valve relay to controller plug. K1 term. 30 -> X1 term. 3, 20
- Controller defective.
1132 Outlet valve VL
SELF-DIAGNOSIS FLASHING CODE 1132
Outlet valve, front left
- Ignition off.
- Pull plug off controller.
- Check solenoid valve resistance at controller plug. X1 term. 11 -> X1 term.
16
Set value: 3...5 Ohm
- Check solenoid valves and leads for short to ground/short to positive, open
circuit and loose contacts as per circuit diagram.
- Check contacts of connectors.
SELF-DIAGNOSIS FLASHING CODE 1112...1222
- Remove solenoid valve relay.
- Check function of valve relay.
- Check ground connection, valve relay. K1 term. 87a -> body ground
Set value: < 0,5 Ohm
- Check voltage supply, valve relay. K1 term. 87 -> body ground
Set value: 10...15 V
- Check lead from valve relay to controller plug. K1 term. 30 -> X1 term. 3, 20
- Controller defective.
1134 Outlet valve VR
SELF-DIAGNOSIS FLASHING CODE 1134
Outlet valve, front right
- Ignition off.
- Pull plug off controller.
- Check solenoid valve resistance at controller plug. X1 term. 11 -> X1 term.
34
Set value: 3...5 Ohm
- Check solenoid valves and leads for short to ground/short to positive, open
circuit and loose contacts as per circuit diagram.
- Check contacts of connectors.
SELF-DIAGNOSIS FLASHING CODE 1112...1222
- Remove solenoid valve relay.
- Check function of valve relay.
- Check ground connection, valve relay. K1 term. 87a -> body ground
Set value: < 0,5 Ohm
- Check voltage supply, valve relay. K1 term. 87 -> body ground
Set value: 10...15 V
- Check lead from valve relay to controller plug. K1 term. 30 -> X1 term. 3, 20
- Controller defective.
1142 Outlet valve HA
SELF-DIAGNOSIS FLASHING CODE 1142
Outlet valve, rear
- Ignition off.
- Pull plug off controller.
- Check solenoid valve resistance at controller plug. X1 term. 11 -> X1 term.
33
Set value: 3...5 Ohm
- Check solenoid valves and leads for short to ground/short to positive, open
circuit and loose contacts as per circuit diagram.
- Check contacts of connectors.
SELF-DIAGNOSIS FLASHING CODE 1112...1222
- Remove solenoid valve relay.
- Check function of valve relay.
- Check ground connection, valve relay. K1 term. 87a -> body ground
Set value: < 0,5 Ohm
- Check voltage supply, valve relay. K1 term. 87 -> body ground
Set value: 10...15 V
- Check lead from valve relay to controller plug. K1 term. 30 -> X1 term. 3, 20
- Controller defective.
1222 Main valve
SELF-DIAGNOSIS FLASHING CODE 1222
Main valve,
- Ignition off.
- Pull plug off controller.
- Check solenoid valve resistance at controller plug. X1 term. 11 -> X1 term.
18
Set value: 2...5 Ohm
- Check solenoid valves and leads for short to ground/short to positive, open
circuit and loose contacts as per circuit diagram.
- Check contacts of connectors.
SELF-DIAGNOSIS FLASHING CODE 1112...1222
- Remove solenoid valve relay.
- Check function of valve relay.
- Check ground connection, valve relay. K1 term. 87a -> body ground
Set value: < 0,5 Ohm
- Check voltage supply, valve relay. K1 term. 87 -> body ground
Set value: 10...15 V
- Check lead from valve relay to controller plug. K1 term. 30 -> X1 term. 3, 20
- Controller defective.
1233 Wheel-speed sensor VL
SELF-DIAGNOSIS FLASHING CODE 1233
Wheel-speed sensor, front left
- Ignition off.
- Pull plug off controller.
- Check wheel-speed-sensor winding resistance at controller plug. X1 term. 5 -
> X1 term. 23
Set value: 0,8...1,4 kOhm
- Check wheel-speed sensor and leads for short to ground/short to positive,
mix-up, open circuit and loose contacts at controller plug. X1 term. 5 -> X1
term. 23
- Check condition of connectors.
- Excessive wheel bearing clearance.
SELF-DIAGNOSIS FLASHING CODE 1233
- Turn wheel, front left and check voltage at controller plug (alternating
voltage). X1 term. 5 -> X1 term. 23
Set value: > 75 mV
- Wheel-speed sensor loose or not flat on mount.
- Ring gear defective (e.g. corroded, dirty, damaged or loose).
- Check number of teeth.
Set value: 43
- Controller defective.
1241 Wheel-speed sensor VR
SELF-DIAGNOSIS FLASHING CODE 1241
Wheel-speed sensor, front right
- Ignition off.
- Pull plug off controller.
- Check wheel-speed-sensor winding resistance at controller plug. X1 term. 7 -
> X1 term. 25
Set value: 0,8...1,4 kOhm
- Check wheel-speed sensor and leads for short to ground/short to positive,
mix-up, open circuit and loose contacts at controller plug. X1 term. 7 -> X1
term. 25
- Check condition of connectors.
- Excessive wheel bearing clearance.
SELF-DIAGNOSIS FLASHING CODE 1241
- Turn wheel, front right and check voltage at controller plug (alternating
voltage). X1 term. 7 -> X1 term. 25
Set value: > 75 mV
- Wheel-speed sensor loose or not flat on mount.
- Ring gear defective (e.g. corroded, dirty, damaged or loose).
- Check number of teeth.
Set value: 43
- Controller defective.
1243 Wheel-speed sensor HR
SELF-DIAGNOSIS FLASHING CODE 1243
Wheel-speed sensor, rear right
- Pull plug off controller.
- Check wheel-speed-sensor winding resistance at controller plug. X1 term. 4 -
> X1 term. 22
Set value: 0,8...1,4 kOhm
- Check wheel-speed sensor and leads for short to ground/short to positive,
mix-up, open circuit and loose contacts at controller plug. X1 term. 4 -> X1
term. 22
- Check condition of connectors.
- Excessive wheel bearing clearance.
SELF-DIAGNOSIS FLASHING CODE 1243
- Turn wheel, rear right and check voltage at controller plug (alternating
voltage). X1 term. 4 -> X1 term. 22
Set value: > 75 mV
- Wheel-speed sensor loose or not flat on mount.
- Ring gear defective (e.g. corroded, dirty, damaged or loose).
- Check number of teeth.
Set value: 43
- Controller defective.
1311 Wheel-speed sensor HL
SELF-DIAGNOSIS FLASHING CODE 1311
Wheel-speed sensor, rear left
- Ignition off.
- Pull plug off controller.
- Check wheel-speed-sensor winding resistance at controller plug. X1 term. 6 -
> X1 term. 24
Set value: 0,8...1,4 kOhm
- Check wheel-speed sensor and leads for short to ground/short to positive,
mix-up, open circuit and loose contacts at controller plug. X1 term. 6 -> X1
term. 24
- Check condition of connectors.
- Excessive wheel bearing clearance.
SELF-DIAGNOSIS FLASHING CODE 1311
- Turn wheel, rear left and check voltage at controller plug (alternating
voltage). X1 term. 6 -> X1 term. 24
Set value: > 75 mV
- Wheel-speed sensor loose or not flat on mount.
- Ring gear defective (e.g. corroded, dirty, damaged or loose).
- Check number of teeth.
Set value: 43
- Controller defective.

4444 No fault stored
COMPONENT/FUNCTIONAL TEST
Checking controller voltage supply
- Check all fuses.
- Ignition off.
- Pull plug off controller.
- Check ground connections at controller plug. X1 term. 1, 11 -> body ground
Set value: < 0,5 Ohm
- Ignition on and start engine.
- Check voltage supply at controller plug. X1 term. 2 -> body ground
Set value: 11...15 V
- Check leads for loose contacts.
ABS warning lamp does not light or flashing codes are not output
- Ignition off.
- Pull off controller plug.
- Check ABS bulb.
- Check diode in valve relay.
- Check following leads and connectors as per circuit diagram for open circuit,
loose contacts, short to positive or short to ground.
* Diagnosis plug connections
* ABS warning-lamp leads to controller and valve relay
* Ground connection, valve relay
Checking stop-lamp switch
- Ignition off.
- Pull plug off controller.
- Check voltage at controller plug:
X1 term. 12 -> body ground
* Brake not pressed: < 1 V
* Brake pressed : > 10 V
- Check stop-lamp switch.
- Check leads from controller plug to stop-lamp switch and fuse.
Brake warning lamp function
- Ignition on.
- Release hand brake.
- Check brake-fluid level and top up brake fluid if necessary.
- If brake warning lamp is always lit, consecutively pull off plugs at
compensating tank and pressure switch.
Replace corresponding component if warning lamp goes out.
- No brake warning lamp function.
Check fuses.
Check lamp.
Use circuit diagram to check leads.
Checking motor relay
- Ignition off.
- Pull plug off controller.
- Check leads from controller plug term. 14 and 32 to hydraulic modulator plug
as per circuit diagram.
- Check pump motor resistance.
Set value: < 1 Ohm
- Check resistance of solenoid (motor relay). K2 term. 85 -> K2 term. 86
Set value: 50...100 Ohm
- Check diode in motor relay.
- Check all ground connections.
Check pressure switch, hydraulic pump and high-pressure accumulator
- Check all fuses.
- Ignition off.
- Detach controller plug.
- Press brake pedal approximately 20 times (to empty high-pressure
accumulator) until there is a noticeable increase in pedal force.
- Connect up ohmmeter to controller plug term. 9 to 10.
Note: Reading greater than 1 MOhm corresponds to contact open and less than
5 Ohm to closed.

- Install (see picture) ATE pressure test connection, part no. 03.9305-0145.2
between pressure accumulator and hydraulic modulator.
- Connect up pressure gauge (250 bar).
- Bleed brake system and pressure gauge.
- Pressure accumulator must have been discharged.
- Ignition on.
* Pressure-gauge reading switches to initial pressure of pressure accumulator
Set value: 40...90 bar
- Check pressure warning switch 9 at controller plug term. 10 and term. S3.
* Brake warning lamp goes out and ABS contact in pressure warning switch
closes at 130...150 bar
* Cut-out pressure,
Set value: 170...190 bar
- Dissipate accumulator pressure.
* Renewed cut-in pressure,
Set value: 130...150 bar
* Pressure build-up time between cut-in and cut-out pressure,
Set value: < 25 s
- Ignition off.
- Pull plug off pump motor.
Ignition on.
- Check ABS warning contact in closing cover of reservoir.
* ABS warning contact opens if float makes contact with lower stop.
- Dissipate accumulator pressure.
* ABS contact in pressure warning switch opens at 100...110 bar.
Brake warning lamp lights.
- Check lead from controller plug term. 9 to ABS warning lamp unit as per
circuit diagram.
Check solenoid valves for proper function and mix-up.
Perform test consecutively for each individual wheel.
Turn appropriate wheel by hand or drive vehicle on roller dynamometer.
Only connect up inlet and outlet valve of one wheel to controller plug.
- Ignition off.
Note: Switch-on duration of solenoid valves max. 10 s.
Check pressure reduction, front left wheel:
- Connect up button of KDAW 9975 to controller plug term. 2 to term. 35 and
jumper term. 35 with 16.
- Ignition on.
- Press brake pedal.
* Wheel blocks.
- Press button.
* Wheel can be turned.
- Ignition off.
- Disconnect button.
Note: Switch-on duration of solenoid valves max. 10 s.
Check pressure holding, front left wheel:
- Connect up button of KDAW 9975 to controller plug term. 2 to 35.
- Ignition on.
- Press button.
- Press brake pedal.
* Wheel can be turned.
- Release button.
* Wheel blocks.
- Ignition off.
- Disconnect button.
Note: Switch-on duration of solenoid valves max. 10 s.
Check pressure reduction, front right wheel:
- Connect up button of KDAW 9975 to controller plug term. 2 to term. 15 and
jumper term. 15 with 34.
- Ignition on.
- Press brake pedal.
* Wheel blocks.
- Press button.
* Wheel can be turned.
- Ignition off.
- Disconnect button.
Note: Switch-on duration of solenoid valves max. 10 s.
Check pressure holding, front right wheel:
- Connect up button of KDAW 9975 to controller plug term. 2 to 15.
- Ignition on.
- Press button.
- Press brake pedal.
* Wheel can be turned.
- Release button.
* Wheel blocks.
- Ignition off.
- Disconnect button.
Note: Switch-on duration of solenoid valves max. 10 s.
Check pressure reduction, rear axle:
- Connect up button of KDAW 9975 to controller plug term. 2 to term. 17 and
jumper term. 17 with 33.
- Ignition on.
- Press brake pedal.
* Wheel blocks.
- Press button.
* Wheel can be turned.
- Ignition off.
- Disconnect button.
Note: Switch-on duration of solenoid valves max. 10 s.
Check pressure holding, rear axle:
- Connect up button of KDAW 9975 to controller plug term. 2 to 17.
- Ignition on.
- Press button.
- Press brake pedal.
* Wheel can be turned.
- Release button.
* Wheel blocks.
- Ignition off.
- Disconnect button.
Note: Switch-on duration of solenoid valves max. 10 s.
Function, main solenoid valve:
- Connect up button of KDAW 9975 to controller plug term. 2 to 18.
- Ignition on.
- Press brake pedal slightly.
- Briefly press button several times.
* Brake pedal must pulsate.
- Ignition off.
- Disconnect button.
If set values are not attained:
- Use circuit diagram to check leads for loose contact and open circuit.
- Check for leaks in hydraulic connections (visual inspection).
- Pull off plug at hydraulic modulator.
- Check plug and spring contacts for corrosion.
- Check ground connection of hydraulic modulator (both screw connections).
- Check ground connection of pump motor.
Check wheel-speed sensors and ring gear
- Ignition off.
- Detach controller plug.
- Start engine.
- Measure with Motortester special input at controller plug.
* Wheel, front left term. 5 and 23
* Wheel, front right term. 7 and 25
* Wheel, rear right term. 4 and 22
* Wheel, rear left term. 6 and 24
Set value: Picture, sinusoidal signal
1 = Wheel-speed sensor
2 = Ring gear
3 = Motortester oscilloscope.

- Turn corresponding wheel.
If available, drive wheels on brake dynamometer (maximum speed and rock
vehicle heftily).
Note: The wheel-speed-sensor output signal must produce a sinusoidal curve,
the amplitude and period of which change as a function of rotational speed. The
amplitude is additionally influenced by the air gap. It decreases with increasing
air gap.
The maximum permissible fluctuation in amplitude for all wheel-speed sensors
is 25 %.
In the event of deviation, check:
- Wheel-bearing clearance.
- Ring gear for freedom of movement, eccentricity error and damage.
- Air gap at several locations.
- Wheel-speed-sensor lead for loose contacts.
- Interference voltage in ABS wiring harness (e.g. distance from ignition cable
must be more than 5 cm).
A test drive is to be performed after repairing the ABS system. In doing so,
drive for at least 1 minute at a speed in excess of 40 km/h.
Then read out flashing code to ensure that there are no further faults in the ABS
system.
ADDITIONAL TEST STEPS
* Specified tire size fitted?
* If ABS warning lamp lights up from time to time when driving (e.g. after
switching on loads) and goes out again automatically, check battery and
voltage supply (alternator, regulator and voltage dips).
* Check tightness of ground strap between engine block and vehicle frame.
* Spring contacts must be properly engaged.
* All plug contacts ok?
Perform test drive as final check:
Drive for at least 1 min. at a speed of in excess of 40 km/h.
Warning lamp must not light.
SET VALUES
ABS inlet solenoid valves
- Set value: 5...7 Ohm
ABS outlet solenoid valves
- Set value: 3...5 Ohm
ABS main solenoid valve
- Set value: 2...5 Ohm
Note: Winding resistances at -10...+120 Grad C ambient temperature.
Solenoid, motor relay
- Set value: 50...100 Ohm
Solenoid, valve relay
- Set value: 50...100 Ohm
Solenoid, wheel-speed sensor
- Set value, front: 0,8...1,4 kOhm
- Set value, rear : 0,8...1,4 kOhm
Note: Winding resistances at -10...+120 Grad C ambient temperature.
Switching ranges of 5-pole pressure warning switch:
- S2 pump motor
Cut-out pressure: 170...190 bar
Renewed cut-in pressure: 130...150 bar
- S3 ABS warning switch
Cut-in pressure: 120...150 bar
Renewed cut-out pressure: 100...110 bar.

- S4 brake warning switch
Cut-out pressure: 120...150 bar
Renewed cut-in pressure: 100...110 bar
Max. perm. switch-on duration:
- of pump motor: 2 min
- solenoid valves 10 s
Number of ring gear teeth
- Set value, front 43 teeth
- Set value, rear 43 teeth
Air gap between wheel-speed sensor and ring gear cannot be adjusted.
Tightening torques:
Wheel-speed-sensor fastening screws
- Set value: 10 Nm
Wheel-brake-cylinder bleeder screws
- Set value: 7...9 Nm
Wheel-hub fastening screws
- Set value: 265 Nm
Tightening torques, front wheel brake:
Fastening screws for brake anchor plate
- Set value: 125 Nm
Tightening torques, rear wheel brake:
Fastening screws for brake anchor plate
- Set value: 65 Nm
Brake-caliper fastening screws
- Set value: 35 Nm
Note: Renew self-locking screws or tighten with locking compound.
Tightening torque for fastening nuts or bolts at hydraulic modulator.
Set value:
1 = 15 Nm
2 = 25 Nm
3 = 25 Nm
4 = 25 Nm
5 = 10 Nm
6 = 45 Nm.

ELECTRICAL TERMINAL DIAGRAM:

B1 = Wheel-speed sensor
HL = rear left
HR = rear right
VL = front left
VR = front right
H3 = Stop lamp
S1 = Stop-lamp switch
W1 = Ground connection next to controller
X1 = Controller plug (35-pole)
X2...X3 = Wheel-speed-sensor plugs with built-in capacitor
X4...X5 = Wheel-speed-sensor plugs
X11...X12 = Diagnosis plug
F1 = Fuse, pump motor
H2 = Brake warning lamp
K2 = Pump-motor relay
M1 = Pump motor
S2 = Pressure switch, pump motor
S3 = Pressure switch, ABS warning lamp
S4 = Pressure switch, brake warning lamp
S5 = Warning switch, brake warning lamp
S6 = Warning switch, ABS system
S7 = Warning switch, hand brake

W2 = Ground connection, negative battery terminal
X6 = Plug at pump motor
X7 = Plug at pressure warning switch
Y3 = Closing cover, brake-fluid compensating tank.

W3 = Ground connection, transmission to hydraulic modulator
Y1 = Hydraulic modulator
A = Inlet valve, ABS front left
B = Outlet valve, ABS front left
C = Inlet valve, ABS rear
D = Outlet valve, ABS rear
E = Outlet valve, ABS front right
F = Inlet valve, ABS front right
G = Main valve, ABS
Y2 = Warning lamp unit
F2 = Fuse, solenoid valves
H1 = ABS warning lamp
K1 = Solenoid valve relay
X8 = Plug, solenoid valves
X9 = Plug, main solenoid valve
X10 = Plug, warning lamp unit 5-pole.

Wheel-speed sensors/ring gear, front axle:
Wheel-speed sensors (1) are located in left-hand and right-hand steering
knuckle (see picture). The connectors are located on the corresponding spring-
strut dome in the engine compartment. Only the fastening screw (2) is to be
loosened on removal.
Note: The air gap cannot be adjusted.
The front wheel brake including wheel hub must be removed on replacing the
ring gear (3); refer to picture.

Wheel-speed sensors/ring gear rear axle:
Wheel-speed sensors (1) are located in left-hand and right-hand rear-axle beam
(see picture). The connectors are located beneath the rear bench seat. Only the
fastening screw (2) is to be loosened on removal.
Note: The air gap cannot be adjusted.
The brake disk has to be removed when replacing the ring gear (3). Lever off
ring gear from inside of brake disk (see picture).