gfs e30: ABS slams the brakes on under full throttle.

[Kershaw]

thread title basically says it all. 1987 325i, 190k, 4 door, 5 speed. mechanically it seems in pretty sound condition. she and i have been apart for a few years, so i dont quite know the maintenance, and she is pretty vague when asked.

i was driving it around, testing things out and all was fine. at the very end, i decided to floor it. i was around 3500rpm before i gassed it and by 4500rpm the ABS slammed the brakes full on. abs light lit up on the dash as well.

what could be the possible cause of this? any ideas on places for me to start looking? water in the brake lines?

[frankenbeemer]

wut

[redhatpat]

I don't think ABS works the way you think ABS works.

[Evan12]

I don't think ABS works the way you think ABS works.

same

[evil_twin]

You claim this is your girlfriend, but in the body of the post you said you have been apart which says shes an ex.

This story is contradicting. I stopped reading.

[jlevie]

I've never encounted a case of spontaneous ABS activation, but start the trouble shooting with:

Troubleshooting the ABS system isn't very difficult. It is a stand alone
system that ony 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 wirng fault in that circuit or a
bad input channel in the ABS unit.