ABS - Functional description

Functional description

ABS electronic control unit M50 is supplied (at pins 12 and 25) directly by the battery by the line protected by maxifuse F5 of the engine compartment junction unit B1.

The ignition-operated supply (INT/A) reaches pin 23 from the line protected by the fuse F42 of under facia control unit B2.

The control unit is earthed via pins 11 and 24.

The four sensors K70, K71, K75, K76 send wheel speed signals tp pins 20-19, 8-7, 22-21, 10-9 of M50, respectively.

Brake pedal switch I30 sends an enablement signal to pin 17 of control unit M50: the ABS cannot intervene unless the brake pedal is pressed. The switch I30 is supplied when the ignition is switched on (INT) from fuse F37 of junction unit B2.

Pin 16 of M50 emits a discrete speed signal that is sent tol Body Computer M1; the same signal is also copied via the CAN network.

Pins 1 and 2 of ABS control unit M50 connect to engine control unit M10, Body Computer M1 and and instrument panel E50 to control the ABS warning light and - if the problem lies in the EBD function - the low brake fluid level and handbrake warning lights. The special 'fault' warning light comes on if there is a problem with one of the above mentioned warning lights.

Self-diagnostic data can be read by connecting to connector C of Body Computer M1- pin 1: it receives signals from pin 6 of the control unit M50 via the special diagnostic line.See E8010 DIAGNOSTIC MULTIPLE CONNECTOR