Read this info, could help!
ABS, ASC, AND ASC+T MALFUNCTION
MODELS AFFECTED: All models equipped with ABS,ASC OR ASC+T
FAULT: Any of the ABS ASC and ASC+T systems inoperative, intermittently inoperative, or illuminating
the warning lamp.
CAUSE: All BMW'S with slip control systems use 4 wheel speed sensors which monitor each wheels
speed of rotation with a high accuracy. The system control unit uses this information to calculate a
vehicle speed. In this way it detects wheel speed variation. If the inputs vary from each other by a certain
amount, the control unit is not able to do the calculation reliably (plausibility fault) and takes its self
off-line as a safety precaution(fail-safe).This can be because the wheels and tires are non-approved partsand therefore do not agree with the system.SOLUTION: Make sure the vehicle is fitted with BMW approved wheels and tires. Then do further
diagnostic testing to check if fault is resolved.
ABS WARNING LIGHT COMES ON
MODELS AFFECTED: All with ABS
FAULT: ABS warning light comes on intermittently. Normal troubleshooting procedures find no defect.
CAUSE: If cars have recently had two new tires, or snow tires put on. Sometimes when the car is driven
over 50 MPH.
SOLUTION: Check all four tires on the car, make sure they are the same brand, style, and size. Check if
any of the new tires have substantially more tread than the rest. These differences may cause enough
variance in rolling diameters to confuse the ABS control unit, which intern gives a false signal to the ABS
Last edited by sycow; 09-27-2005 at 06:46 PM.