Loading ...This answer is applicable for many BMWs in addition to the one listed below.
Q
car year: 1995
car model: M3
I have an intermittent ABS light on the dash that, of course, nevers shows up when I take it to the independent mechanic I use. The light comes on usually after driving for 5-6 minutes. I’m thinking it may be a wiring issue. This all started after flushing the system a while back. How can I determine what the ABS problem is? FYI… I have a code reader from you folks, will it read the code?
A
My first thoughts are that you may have a faulty wheel speed sensor or, perhaps, a corroded or “dirty” toothed gear-wheel (the toothed ring that the sensor reads as the wheels turn). You can check the resistance of each sensor (they should all be within 10% of each other), but if the problem is intermittent, this may not show anything. You can also remove the sensors, inspect and clean them (look for problems at the harness connection point at the sensor and the plug), and attempt to inspect the gear-wheel teeth through the sensor mounting hole. Of course, there could be other faults in the system.
Note the “teeth” on the end of the wheel bearing hub assembly:
If any of the sensors are suspect due to resistance testing or visual inspection issues, they can be replaced easily. If the toothed gear-wheels look suspect due to corroded or missing teeth, these are replaced via replacing the front wheel bearing assemblies or the complete rear axle half-shaft assemblies.
Click below for BMW ABS wheel speed sensors:
Finally, you can have the internal fault codes for the ABS system checked. When the fault light comes on, a fault code is stored in the system controller. The light does not have to be currently on to access the codes. This must be done with the full GT-1, MoDic or DIS type of diagnostic tool that a BMW dealer or well equipped independent shop would have. Your engine fault code reader will not access the ABS system. Unfortunately, at this time, there are no consumer type ABS code readers for BMWs.
