Light is not on at start up but will come on once i start rolling. I checked faults and did not find any ABS faults. I read in an old thread it could possibly be a wheel ring sensor, I have no Idea what that is. Problem started a day or two after installing basket weaves, I don't know if that has anything to do with it.
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Dirty/bad wheel speed sensor, most likely.
Originally posted by ROLLingKINGOriginally posted by slammin.e28 -
How would I go about finding out which one is bad?Comment
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Troubleshooting the ABS system isn't very difficult. It is a stand alone
system that only gets input data from the brake light switch, wheel sensors and
system power. The parts of the system are the ABS module located next to the
steering column, the ABS relay mounted above the ABS module, the ABS unit in
the left front of the engine bay, and a wheel speed sensor at each wheel.
If the ABS light comes on with ignition, but doesn't go out when the engine
starts, a wiring problem, bad module, or bad ABS relay are the likely
candidates. A failed or weak alternator will also cause this because the
system voltage won't rise enough. There is a fusible link inside the ABS relay
that can be blown. The relay can be repaired, or better yet replaced.
If the ABS light comes on when you turn on the ignition, goes out when the
engine starts, and then comes back on before the car is moving the cause could
be a bad module, a bad ABS unit, or a wiring fault.
If the goes out after engine start and only comes one when the car is moving,
there's a problem with one (or more) of the sensors. The simple test to find
out which sensor(s) is the cause is to disconnect all but one of the sensors
and drive the car. If the light comes on, that sensor is sending a speed
signal to the ABS and is good. Repeat with each other sensor to find the
one(s) that don't cause the light to come on. Since the ABS module has no
speed input besides the wheel sensors, if only a bad sensor is connected the
module can't tell the car is moving and thus doesn't fault on missing speed
signals from the other wheels. Once a bad speed sensor is found, if a new
sensor still doesn't work, there could be a wiring fault in that circuit or a
bad input channel in the ABS unit.The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, ALComment
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Finally had time to check out my car this weekend. When I was visually checking all the speed sensors I found out that something had cut the left front wheel speed sensor and Brake pad wear sensor wiring. I repaired the wiring and everything worked fine. Thanks for all the info guys.Comment
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+1
Exact same thing happened to me execpt it was the right front for me. I think the wire was too close to the wheel and probably got somethign caught on the tire which caused it to cut the wire. Repaired the problem with butt connectors and tons of electrical tape and works like a charm. Weird!1991 318i Sedan
2005 X5 3.0i Sport
2010 328i M-Sport Touring
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Can air in the abs unit cause the light to turn on at ignition, stay on at start up and not have working abs? I have replaced the abs module and no change in problem.Kevin Gibson
90 325isComment
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So as stated above, ABS light on at ignition and stays on at start-up is either ABS Module or ABS relay? The relay being the little silver box measuring roughly 1"x1"x2" vs the module, the silver box above your left knee measuring roughly 2" x 1" x 5"?
ThanksKevin Gibson
90 325isComment
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To tag onto this post for future people: if I use a volt meter, how can I test the ABS sensors?Comment
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