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ABS System - Activates When Coming to a Stop

GROUP 34
Brakes

Bulletin Number
34 08 01

Woodcliff Lake, NJ
October 2001
Service Engineering

SUBJECT:
ABS Activates when Coming to a Stop

MODEL:
E46 (3 Series) with DSC - Vehicles produced before 9/2000

SITUATION:
ABS activates when coming to a stop. No fault codes are stored. Braking performance is not affected.

CAUSE:
DSC module individually senses the wheel speeds of each wheel. For ABS to activate, the DSC module senses one wheel moving at a slower rate than the other three wheels.

The problem may be caused by a sensor wiring fault, a contamination fault, a speed sensor fault, or a pulse wheel fault.

PROCEDURE

To locate the source of the problem, using MODiC, select Diagnosis, select DSC Stability Control, and perform a short test, then select Control Unit Functions.

On the Control Unit Functions screen, select DSC Stability Control/Diagnosis requests DSC, then highlight all four wheel speeds ("Wheel speed, front left", "Wheel speed, front right", "Wheel speed, rear left" and "Wheel speed, rear right"). Press "Display" to display each of the wheel speeds.

The following must be performed by two people - drive the vehicle under the conditions necessary to reproduce the fault, at the same time monitoring the displayed wheel speeds on the MODiC. Identify the wheel showing a lower wheel speed.

To troubleshoot the problem circuit - select Function Selection / Complete vehicle / Chassis / Stability Control / Dynamic Stability Control. Then select the appropriate wheel-speed sensor (rear left, rear right, front left of front right).

Press "Test plan" and follow the diagnostic path in the DIS to identify and correct the root cause of the problem (sensor wiring, sensor, pulse wheel or contamination).

WARRANTY INFORMATION
Information only