E30 brake lights not working, keep blowing fuse #6

[bemmergirl]

So I recently completely stripped the car and had it repainted. When I reassembled it I installed Depo smoked taillights. They worked fine for about a week. Now all the other taillights work, except for the brake lights. When I change the fuse, the brake lights come on once, and then the fuse blows and they're dead again. I even increased the fuse to a 15 and it still blew. Electrical is not by forte, so please be gentle. Thanks in advance!

[323i E30]

I'm not going to be of that much help, but do note that the important thing of a fuse is that it's the weakest link in the circuit.
Increasing it will only cause another section of your wiring to be your weakest link and cause fire/damage there.

While I'm in here.. Sounds like you have a short somewhere. Since the taillights are new to the mix, I'd suspect those first if you also changed the cap that holds the bulbs.
I'd twist the old one(s) back on and see if that also hurts the fuse. Should be an easy test.
That or connect them one at the time and see which one is the culprit.

According to google 15A is the correct one there if you have a third brake light. Otherwise use a 7,5A.
The 7,5A sounds like the safest bet if everything was working nicely before.

[bemmergirl]

Thanks for the response. I began tracing the wiring starting at the brake peddle. The wiring harness that connects to the brake light switch crumbled in my hand. While it was not the main problem, it gave me one more fix to attend to. You don't by chance have a part number for that harness do you? It's a two prong connection, but I can't seem to find it anywhere. So after taping up the harness temporarily I headed back to the tail lights.

I disconnected them and the fuse still blew. So I traced back to the brake light relay, near the antenna, and disconnected it. It didn't look corroded but it's hard to tell. After cleaning it a bit, I reconnected it and the tail lights and everything worked. I changed the fuse back to the 7.5 and everything worked fine for about three days.

Ugh. Back to the drawing board. My next plan is to trace the wires threw the car interior. They run down the driver's side, and under the back seat. Any suggestions you have would by appreciated.

[ELVA164]

Maybe check that ground under the left side of the rear seat bottom, see if that's loose and/or corroded.

[bemmergirl]

Mystery solved. While completing some routine maintenance on the front of the engine, I noticed the wiring harness had been crimped and several wires had been damaged. Cleaned and repaired the wiring, brake lights now working fine. (Kinda wonder if this happened at the paint shop.) Glad I found the problem cause I would have never thought to look at the wiring harness at the front of the car.