1990 525i, ALL rear brake lights are not working

[notesguy]

I had it inspected yesterday and the guy said none of the rear brake lights worked. He said it might be a circuit board or it some other part.

Any ideas how to check it myself? (I'm not a mechanic)

Thanks.

[Jimmy535i]

Check/replace the stop/brake light switch. It is located under the dash on driver-side and mechanically operates when brake pedal is depressed. These are a pretty common problem with E34. Should run you under $20 from BMA.

It is a bit of a pain to change but not very difficult.

[Mr Project]

Also carefully inspect the wiring harness as it goes down the trunk arm and up behind the CD changer brackets. Very common for the harness to rub and crack and be cut in that area. Peel the black protective tape off and examine each wire carefully.

If you have cracks/breaks in wires, you'll need to replace them or have them replaced. I just soldered in new wire and used heat-shrink to protect everything. Not hard, just tedious.

[Paul in NZ]

normally the brake light swith failure will give you a "ding..brale light circuit" or similr warning,and if the bulbs are out that wold give you a warning too,maybe a wire brake or fuse??