E39 528I intermittant electrical issues

[johnex]

I just purchased a 2000 528I 74,000 miles. This is my first Bimmer and I'm hoping that some of you can give me some insight on the following:

After I start the vehicle, sometimes I the airbag indicator light is on. When this occurs, my horn and my radio does not work. The radio has no power. When I shut off the engine and re-start, the radio and the horn works and the air bag light is no longer on. The problem seems to correct itself after turning off the engine and re-starting.

Also, the BRAKE light comes on occasionally. The previous owner just changed the pads. Not sure why the brake light is coming on because everything associated with the brakes seem fine. A friend told me that it might possibly be the brake light switch??

Also, the transmission light intermittantly comes on. Today, it has not come on yet.

Everything else on the vehicle works properly. Outside of the above electrical quirks, there are no problems with the car.

Any ideas as to what might be causing the above problems?

Thanks,

John

[Starmavin]

The air bag and horn issue sounds like a bad clock spring harness in the steering column. Could also be an unloader relay. Tough enough to troubleshoot that one in person.

As for the brake light, check your fluid.

Transmission light, check the condition and level of the fluid.

[superdeadman]

as far as brake light goes - maybe one of the sensors is bad? or bad connection?

[ozarkmark]

Make sure the wear sensor for the brake is connected and not damaged. Generally these have to be replaced when you get new pads.

Ditto the fluid checks on the brakes and tranny.

[da_bull]

Yup I had the same thing, I replaced the wear sensor and took care of the brake warning. There are two, one on the left front and one on the right rear.

[Phil528i]

Hi Johnex
I had many of the same problems with my 97 528i. The SRS light was on, the stereo etc stopped working sometimes. I spoke to a few Autoelectricians around Brisbane Australia who couldn't explain it. I was referred to a guy that specialised in European cars who straight away traced the problem to the ignition. He replaced the ignition and all was good. That was about 1 year ago. Now I have Brake Warning Light on all the time. I have recently replaced the pads, rotors & sensors. The mechanic has checked it over twice and it is not a mechanical problem. So off to the Autoelectrician I'll go. Hope this has helped, and if anyone can assist me further with my brakes I'd appreciate it.

[CosmosBlack]

Yes, the ignition module is often the culprit to electrical gremlins.
Especially if it's on and off and affects various different areas at the same time.

[Dirty_Tool]

Its actually not a module but the electrical portion of the ignition switch. This is a fairly common problem on these cars. Try using the vanity lights on the sunvisors. Often times this will make lights go on and off in the cluster. It was pretty wild the first one I ever saw. Since then I have seen several on both e46 and e39. I think you can be failry confident that this will fix 90% if not all of your gremlins that you are experiencing at the moment,