Anti-Lock and Brake Lining lights on.

[ashton]

Both my anti-lock and braking lining light are on in my 88 325i. The brake lining light only comes on when I hit a bump and then it'll go off when I hit another bump. My brakes don't work the first time I press them, but they work the second time I press them. What all can I do to fix my problems, and what do I check? Thank you.

[jlevie]

The brake lining light could be a bad connection at a sensor, a bad connection at the cluster or a problem in the cluster.

Troubleshooting the ABS system isn't very difficult. It is a standalone 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 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 light goes out after engine start and only comes on 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.

Worn down pads can back off from the rotors while driving enough to require one pump on the pedal before the brakes work well. There could be other problems, but if the pads are worn down I'd start with a new set of pads.

[ashton]

Thanks for the info, Jlevie. Sounds like you know what you're talking about.

[dogsbark26]

The brake lining light is almost certainly due to a bad solder connection on a resistor on the instrument cluster circuit board. It is a common fault in e30s.

Here is what I have in the way of write up to fix it.

https://docs.google.com/document/d/1YnVtxr6oydr0cnypx-7lvGeyaeGh0bVM4LkIgPgmopI/edit