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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
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 parts
and therefore do not agree with the system.
SOLUTION: First make sure the wires to the sensors on the wheel hubs are in good condition and the plugs are securely in position.
If the sensor teeth on a hub are badly rusted the sensor may not catch the signal reliably.
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
warning light.

ABS WARNING LIGHT GLOWS
MODELS AFFECTED: 3 series (E 36)-vehicles produced 1/96 to 3/96 without ASC.
FAULT: On rare instances the ABS warning may glow slightly after other electrical consumers have been
switched on. No fault is stored in the ABS control module fault memory.
CAUSE: Hardware fault in the ABS control module.
SOLUTION: If this is encountered replace the ABS control module.

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