More brake light issues - LCM won't turn on center light

[Bdc101]

I was able to fix my side brake light issue by fiddling with it. But I noticed while troubleshooting that the center brake light doesn't come on at all. I did not know this because there was only an error message in the dash for the side light.



I pulled the center brake light off the car and hooked it up to a 12v battery, and it works fine.



I checked LCM codes with my Foxwell and it says no codes.



I looked at the wiring diagram in my Bentley manual (RIP newtis) and there is no fuse. The wire comes directly from the LCM with no fuse or relay.



Other than a broken wire, what could be keeping the light from working? Any suggestions?

[Bdc101]

Just to follow up on this. I found that the power wire for the brake light (black w/ yellow stripe) was broken inside of the flexible loom that goes from the tailgate into the body. I haven't had time to solder a new one in yet, but I am totally sure that is the problem.

[jdstrickland]

The center brake light should work from the brake pedal. The LCM should not play a role. The brake lights should work separately from the lighting system because the brakes will operate at any time.

The broken wire in the harness that goes from the tailgate into the roof will certainly give you the symptom you have. Since you are there, check for other wires to be broken also. This was a common problem with the E36s.

[Bdc101]

The wire actually comes straight out of the LCM, no fuse or switch.



For that matter, why do the brake lights not turn on when I press the brake pedal and the key is not in? Seems like the lights should turn on.

[Effduration]

Originally Posted by Bdc101

Just to follow up on this. I found that the power wire for the brake light (black w/ yellow stripe) was broken inside of the flexible loom that goes from the tailgate into the body. I haven't had time to solder a new one in yet, but I am totally sure that is the problem.

Thanks for following up on this...broken wires in that rubber conduit are very common in the E46...and we are starting to hear more and more about the same issue in the E53 world...

[oldskewel]

Originally Posted by Bdc101

The wire actually comes straight out of the LCM, no fuse or switch.

For that matter, why do the brake lights not turn on when I press the brake pedal and the key is not in? Seems like the lights should turn on.

That's how my 2001 3.0i is as well. I think I've noticed that my German cars are like that (brake lights require key to ON) and my Japanese cars are the opposite - so for the Japanese cars, the brake lights are always ready to turn on when the brake pedal is pressed, key in or not.

The actual wires going from the final connector to the 3rd brake light (24-element LED bar) are blue and brown, +12V when brakes applied, brown is ground.

[RocketyMan]

Originally Posted by Bdc101

The wire actually comes straight out of the LCM, no fuse or switch.



For that matter, why do the brake lights not turn on when I press the brake pedal and the key is not in? Seems like the lights should turn on.

You are correct.
I love looking up diagrams. Anyway, here is the LCM and the wiring to the center brake light. SW/GE is Swartz/Gelb which is black with yellow stripe. Do notice that the "30" inside the module corresponds to "KL30" which is denoted as "hot all times." Therefore, your assumption of the brake lights being able to work regardless of key position should be correct.




I did find that a 2003/09+ has a difference for the raised brake light. It's designated as 54. The terminal designation "54" is denoted as "stop lamps." The ones with 58 are denoted as "Side-marker lamps, tail lamps, license-plate and instrument illumination." Maybe this is a difference? Do the LCI E53 only have stop lamps work with key in position 1 or higher?