[rootehound]

2010 X3 150k miles -- About 3 weeks ago, I had the brake and 4x4 lights come on. Since it wasn't the three lights of doom, I assumed it was a wheel speed sensor.

About a week ago, after being in a store for about 20 minutes, I started the car and had the brake / 4x4 / transmission / airbag / seatbelt (even though it was on and buckled) and bulb warning lights all come on at once. I drove the car about 1/2 mile - it was not in limp mode - pulled over and restarted it,. All the lights except the brake, 4x4 and airbag lights went out. When I started it the next morning ALL the lights were out. About a day later the brake / 4x4 and airbag lights came back on.

Sunday, while driving in a rainstorm, the wipers went berserk. They would start, stop halfway up, stutter back to their parking position, stutter back up, etc., etc. The rear wiper quit completely. This went on for the entire ride home and when I started it Monday morning.

I drove about an hour to a friend's house - he has a scanner that can read BMW codes - and halfway there the wipers started working as normal, and the brake / 4x4 / airbag lights went out.

The scan showed a low voltage fault - (I think that's what it was, I can't remember exactly) in the Body Control Module and brake pedal switch. (Oddly, there was no code for the wheel speed sensor) I also did a load test on the battery and checked the charging system and they were fine.

Since they were not very expensive, I ordered a used BCM and a new brake pedal switch.

Am I missing anything? Is it really possible for the BCM and/or brake switch to cause all these issues?

I thought I was past this type of stuff when I stopped driving British cars about 20 years ago. ;-)

[benmannell]

Hey there, this sounds similar to an issue I had recently. All sorts of weird electrical issues that had the feeling of costing HEAPS of $$ to diagnose. Turns out the culprit was a dirty contact in the ignition switch. Simply removing the ignition switch, cleaning the contacts with electrical cleaner, reassembling, fixed it for me!
Hopefully this is the issue for you also!

Here's the guide I followed: https://www.e46fanatics.com/threads/...atomy.1018686/

A quick way to confirm this may be your issue too, would be using a multimeter to probe in the fuse box and see if one bank of fuses is receiving significantly lower than 12V. This was the case for me.

[GT4560]

While reading the original post...i was inclined to think weak battery.
In addition I would check the voltage regulator for the alternator.

[AZ X3]

I suspect I have the same issue. One block of fuses, top left are showing about 4-5 volts, which includes the radio among other things. Going to try the ignition switch fix.