Does it stay on right away or turn on when moving? (archive)

THE LIGHT STAYS ON WHEN YOU START THE CAR
If it stays on when you start the car, you may have a broken sensor wire, or a bad relay on the ABS Hydraulic Unit.

Also, the ABS ECU monitors the alternator charge signal, which runs between the alternator and the battery light. If the voltage at that wire is too low (i.e. the battery isn't charging), the ABS light will be on. It's the blue wire at pin 15 of the connector at the ABS ECU, and it should run to the alternator and to pin 12 on the diagnostic connector. Of course, it also runs to the instrument cluster, where it eventually connects to the battery light.

THE LIGHT TURNS ON ONCE YOU START MOVING
Most likely the problem is that a wheel speed sensor isn't getting a sinal from its pulse wheel. This could mean the sensor isn't close enough to the pulse wheel, or it could mean a puls wheel is dirty or rusty. The pulse wheels are the ribbed wheels at each hub. Clean 'em. If that doesn't do it, you may have to replace 'em.

What is probably the problem that will cause a 1986 528e's anti-lock brake light to stay on all the time ?

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