ABS, DSC, Brake Light Troubleshooting...

Originally Posted by bobzdar

It ended up being the front left sensor, which jives with the gps not working. So sounds like the easy way to diagnose is if the gps stops working, its left front, if the speedo stops working, its left rear, if the cruise stops working its right rear and if nothing stops working, its the front right.

I think this should be added to to all of the forums... I have an e46 and was trying to determine why these 3 lights came on. (I found the above quoted message from the 7 series bimmerforums.com) Called 2 different shops to get a quote for their diagnostics charges, and decided after I read this post, to just take a look myself. I started with the drivers side since the way I park keeps me from getting to the right side. There were no issues on the driver side.

When I flipped it around and pulled the front right wheel, I saw the Wheel Speed Sensor hanging there, not connected to the hub, I looked back there and the head of the bolt had broken off and allowed the speed sensor to fall out of hole. I could not get the broken thread out so for a temp fix, I added some silicon to the speed sensor's bolt location and plugged in back in the hole.

Took it for a test drive and when I got over 5 to 10 mph, all the lights went off... DING DING DING, we have a winner.

So from quote above, here is how it breaks down...

If all 3 lights are on.. (ABS, DSC, Brake) then also check if another system has issues...

Driver Front Wheel controls - GPS
Driver Rear Wheel controls - Speedo
Pass Front Wheel controls - (has no extra function)
Pass Rear Wheel controls - Cruise Control

Another thing I found useful was a Youtube video to check if Speed Sensors were sending data. Works on cars with Nav, dont know how to do it without Nav.

Go into Settings Menu, then hold down Menu button for 10 seconds, this brings up a new menu, go down to Sensor Check. Also check on youtube if you have IDrive... There are a few videos that tell you how to get into the Hidden Menus.

Hope this helps.
RC_a_