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Control module

Control module


The control module is integrated into the TC/ABS unit and has a 31-pin connector.

A wheel sensor at each wheel sends a wheel-speed signal to the control module.

The ABS works in such a way that the solenoid valves (inlet and outlet valves) and return pump modulate the hydraulic brake pressure when any of the wheels is retarded more than the others. The pressure can either be maintained at a constant level or can be reduced so that maximum braking power will be achieved by each individual wheel on the prevailing road surface.

The EBD function incorporated in the control module controls the distribution of braking power between front and rear wheels by means of solenoid valves (inlet and outlet valves).

The TCS function of the control module always utilizes the friction of the driven wheels to maximum effect during acceleration. Limited wheelspin is modulated by applying the brakes and requesting the Trionic for engine torque limitation. The control module activates the pressure-increase valve, the pressure-relief valve and the return pump to build up and modulate the pressure to the driven wheel that is to be braked if wheelspin in excess of the permissible limit occurs.

The control module receives a continuous power supply from the +30 circuit and is designed for a working voltage of between 9 and 16 V.

When the ignition switch is turned to ON, the control module is activated and the ABS, TCS OFF and TCS lamps come on as a function test. They go out after 3-5 seconds if no faults are present in the systems.

Always ground yourself, e.g. on the engine block, before touching the control module and avoid touching the terminal pins.

The control module incorporates the following components:


• Main relay

• Pump relay


Main relay

The integral main relay supplies power to the solenoid valves and pump relay and cannot be replaced separately.

Pump relay

The integral pump relay supplies power to the return pump and cannot be replaced separately.

Diagnostics

The control module monitors its own internal functions as well as the components of the TC/ABS system.

If an internal fault occurs in the control module, diagnostic trouble code C1605 will be set, the TCS and ABS functions will be disabled, and the warning lamps for ABS, brakes, and TCS OFF will light up as well as the central warning lamp.