Drivers Side brake light not working - brake pedal switch?

[RRdawho?]

There seems to be an issue with my driver's side brake light.

The tail light works fine, flashers, reverse etc. However the brake light and tail light brake light are not working on the drivers side.

I checked fuses, fine.

I checked bulbs, fine.

I took off the taillight housing, and hooked up a 9v battery to test every port where the harness plugs in, and all the lights light up fine.

So that rules out the bulbs, housing, and fuses.

My only guess now is either one part of my wiring harness has gone bad (just the brake wires) or the brake light switch at the pedal is going bad.

Question I have is wouldn't the brake pedal switch going bad affect both passenger/driver side brake lights, or is it possible for only one side to go bad before the other one starts going bad too?

TIA,

Rich

[ponchiz318]

It isn't the brake pedal switch. I had the exact same issue when I had my e36. Check the bulb socket itself. Mine was a bit corroded and wasn't making proper contact with the bulb. I bought a new socket and bam!, instant fix.

[RRdawho?]

Can't be the bulb socket.

As i mentioned earlier in my thread, I tested the bulb, sockets, and even the harness pins on the housing w/ a 9v battery. All the bulbs light up fine in all tests.

[UnderCoverGuy11]

Have you checked the trunk lid wiring? If you were having a break in the connections anywhere, I would start there first, the trunk has a bundle of wires on the drivers side where the hinge is, unwrap and check for any exposed copper and repatch

[BMWMPow3r]

Have you checked the trunk lid wiring? If you were having a break in the connections anywhere, I would start there first, the trunk has a bundle of wires on the drivers side where the hinge is, unwrap and check for any exposed copper and repatch

+1, you'll want to check those anyways.

[bmb527]

If either brake light is not working, you will get a message on your OBC. There are 2 messages pertaining to brake lights. If memory serves, the one that says "BRAKE LIGHT CIRCUIT" is the brake light switch.
The wire harness on the left trunk hinge USUALLY causes a short and fuses blow. To find exactly where it breaks, look at where it bends and flexes. Now, open the sheath up and you will see your issues. It is easy to fix, but so is the brake light switch, which is my best guess as to where your problem lies. Happy fixin'!!

[JDStrickland]

The Brake Light Switch will not cause the lights on one side of the car to not work while the ligths on the other side are good.

Your test is flawed. You seem to have looked at the lamp housing, but have you looked at the wiring -- specifically the pins inside of the connector?

[RRdawho?]

If either brake light is not working, you will get a message on your OBC. There are 2 messages pertaining to brake lights. If memory serves, the one that says "BRAKE LIGHT CIRCUIT" is the brake light switch.
The wire harness on the left trunk hinge USUALLY causes a short and fuses blow. To find exactly where it breaks, look at where it bends and flexes. Now, open the sheath up and you will see your issues. It is easy to fix, but so is the brake light switch, which is my best guess as to where your problem lies. Happy fixin'!!

Wiring harness at driver side trunk are where it sees flex is fine. No bad wires when I took off the shielding.

Fuses also look fine. (1 fuse for both brakes lights), box has no blown fuses.

The Brake Light Switch will not cause the lights on one side of the car to not work while the ligths on the other side are good.

Your test is flawed. You seem to have looked at the lamp housing, but have you looked at the wiring -- specifically the pins inside of the connector?

I'll check this. I believe my ground wire is fine as the driving lights are fine, reverse, and flashers. Pins look correct with no corrosion.

[GQ_Style]

I have the same problem on my 94 318i. Bulbs are fine. Socket is fine. I did a continuity test from the socket slot to the harness plug on the taillight housing, and I get 100%. I test to see if I get power from the harness for the brake light and nothing comes though.

I'm going to run a splice from the passenger side brake light over to the driver side brake light as a workaround. Let me know if you ever figure this out. I spent 3 hours trying to track this down.

Brake switch is fine as the other 2 brake lights do come on.

[persiandude]

Did you end up figuring this out? I know its been 7 years since the last post.

My driver side brake light is out (and just recently the reverse light). The tail light and indicator both work. The passenger side works for all lights and the 3rd brake light works as well.

[spyderg0d]

Ya know.. I wonder why some of these posts get saved when there's no conclusions.

But he probably lost a ground at the ground spade connector thats under the driver seat carpet.. All the grounds for the rear lights run to that spade connector.
The brake lights run together, the reverae lights run together. Its either the bulbs, the sockets, the plugs, or the wires. If 1 side of the reverse and brake light works, the switches and the power side of the circuit is probably fine. Also, check the trunk wire loom..

[persiandude]

ok thanks - I will check the connector under the carpet - the wires in the trunk look look ok. the tone generator that I bought to test sucks and was worthless.