SOP

���(Anti-lock Brake System, ABS- Connection Of Wheel Sensor And Valves:

WIRING DIAGRAMS

Anti-lock Brake System: Component Location:

COMPONENT LOCATION VIEW

Anti-lock Brake System: Component ID:

COMPONENT ID
22A Main fuse board in the dashboard.
29 Brake light switch on the pedal assembly.
47Q ABS warning lamp in the main instrument display panel
110 Tachometer (rev counter) in the main instrument display panel.
296 ABS valve block integrated with the brake unit, behind the battery.
297 Motor, hydraulic pump, integrated with the brake unit, behind the battery.
298A Wheel sensor, left front, on left-hand steering swivel member.
298B Speed sensor, right front wheel, on right-hand steering swivel member.
298C Speed sensor, left rear wheel, on left rear wheel hub.
298D Speed sensor, right rear wheel, on right rear wheel hub.
342A Main fuse board, in engine bay, on main relay board.
430 Trionic control module behind side trim on right-hand side.
445 Data link connector under the dashboard adjacent to the steering column.
505 Motronic 2.10.2 control module on right-hand side behind the side trim.
507 TCS control module under the right-hand front seat.
508 Cruise Control system control module in engine bay on right-hand side below the windshield.
510 Motronic 2.8.1 control module on right-hand side behind the side trim.
540 Main instrument display panel on the dashboard.
547 ABS control module integrated with the brake unit behind the battery.

4-Pin Connector
H4-6 On the bracket below the left-hand A pillar.

6-Pin Connector
H6-3 On the hydraulic unit.

10-Pin Connector
H10-6 In left-hand B pillar.

33-Pin Connectors
H33-2 Black connector on bracket below the left-hand A pillar.
H33-4 On the bulkhead partition behind the glove box.

Grounding Points
G30 Grounding point, left-hand structural member behind the battery.
G33S Grounding point, connector bracket (Signal) below the left-hand A pillar.

DESCRIPTION OF OPERATION
The system consists of the following:
^ Control module 547
^ Wheel sensors 298A-D
^ Brake unit (including valve block 296 and return pump 297).

The anti-lock brake system is a dual-circuit, three- port braking system. Four wheel sensors send speed information from each wheel to the ABS control module.

This information is used by the control module for continuously calculating wheel speed, wheel acceleration (speed increase), wheel retardation (speed reduction), road speed and wheelspin (degree of lock-up).

The ABS control module controls the valves and if a wheel tends to lock up, the valves in the valve block adjust brake application so that maximum braking effect is transferred to the road surface at all times.

Control Module 547
The control module is integrated with the brake unit and supplied with +30 circuit current via pin 2 and with +15 circuit current via pin 1 of the 4-pin connector when the ignition switch is in the Drive position.

The control module is grounded via pin 3 of the 4-pin connector.

Hydraulic Pressure.
Whenever the car is driven off, the return pump starts up so that the control module can check its operation.

Solenoid Valves.
Each valve in the valve block has three functions. These functions are:
^ Pressure increase (normal position)
^ Pressure retention
^ Pressure relief

Pressure Increase (Normal Position)
In this position the solenoid valve is not supplied with current.

This is the normal position for ordinary braking without ABS control and the pressure increase position for ABS braking.

During ABS braking the control module can initiate up to 10 braking cycles per second.

Pressure Retention Position
The solenoid valve is supplied with half current intensity from the ABS control module.

This is one of the three positions the ABS control module uses during ABS braking (pressure increase position, pressure retention position and pressure relief position).

Pressure Relief Position
In this position the ABS control module is supplied with full current intensity.

The control module supplies the hydraulic pump with current and the pressure can be pumped back to the master cylinder.

Equalization Valve
To allow both rear wheels to be controlled by only one solenoid valve, a pressure-controlled equalization valve for the rear wheel circuit is provided in addition to the solenoid valve.

The equalization valve ensures that the same brake pressure is applied to both rear wheels during ABS braking.

During ordinary braking without ABS control, brake pressure to the right-hand rear wheel passes through the solenoid valve (normal position) and brake pressure to the left-hand rear wheel through the equalization valve.

Wheel Sensors
The control module is provided with wheel speed information on the following pins:
Left Front:
Pin 4
Pin 5

Right Front:
Pin 20
Pin 21

Rear Left:
Pin 9
Pin 10

Rear Right:
Pin 6
Pin 18

Wheel Speed Information
The ABS control module processes the information and makes it available to other systems which require speed information.

These systems are:
Pin 7 (from right front wheel):
Motronic 2.10.2
Motronic 2.8.1
Trionic
TCS

Pin 17 (left front wheel):
Cruise Control system
TCS

Pin 19 (right rear wheel):
TCS

Pin 22 (left rear wheel):
Main instrument display panel
TCS

Speed information is provided even if the ABS system is inoperative and the ANTI LOCK lamp is on.

ABS (ANTI LOCK) Warning Lamp
The control module grounds pin 1 (2-pin) and pin 4 (4-pin) for 3 seconds when the ignition is switched on to test the warning lamp. The wheel sensors and solenoid valves are tested at the same time. If everything is OK the warning lamp goes out.

Should a fault arise when the car is being driven, the warning lamp will light up and the anti-lock brake system will be disengaged.
The warning lamp will also light up if the current (+15 circuit) supplied to the control module fails.

FAULT DIAGNOSIS IN THE ABS SYSTEM
Fault diagnosis is to be carried out by means of an ISAT scan tool.