MICROPROCESSOR CONTROLLED ABS(uC-ABS)STORES ERRONEOUS INTERNAL DEFECT FAULT
MODELS AFFECTED: 7series(E32)-vehicles produced 06/91 and later, equipped with M30 engine.
5 series (E34)-vehicles produced 9/91 and later.
FAULT: Increasing number of uC-ABS control units are being returned for showing internal defect during troubleshooting and readout of the fault memory. In most cases the fault is erroneous.
CAUSE: If the ignition is switched on with the cap of the D100 diagnostic connector removed, the erroneous fault can be set by a low voltage condition on the TTD lead to this control unit.
SOLUTION:
-Erase the fault in the uC-ABS fault memory, while the diagnostic module is still connected and the ignition is switched on.
-Before disconnecting the diagnostic cable, switch off the ignition
-Reconnect the cap for the D100 diagnostic connector, then switch on
the ignition again.
-Do not replace control unit.
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.
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Advanced Hints and Tips : BMW ABS problems