Hi,

Sorry for jumping on this old thread, but I thought it was better than starting a new one.

My 2006 MCS developed this issue recently.

Brake lights stuck on when ignition key is in position 0 or key is removed. Brake lights function normally otherwise.

My BCM looks dry and there has never been water or dampness in this area. The car has been garaged and not used much in the last year.

Wondering if anyone has found a definitive solution when there is no external diode.

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Did you ever find a solution?

 

Curious no one has found a solution on the LCI cars. Just went through this on our 2003 R53 Grumpy. I started with a switch because it was cheap, easy, and fairly common, but it did not fix the issue. Found the diode, it's wasted, even though we've never had water ingress issues with the car. I guess 212k miles has taken it's toll.

Does anyone know the purpose? Will it hurt anything to leave it out? I mean, I get that a diode basically works as a check valve only allowing electricity to "flow" one way. But does the circuit really need it? The lights work properly without the diode and I've seen other mentions to just bypass it.

 

I have an 05 with no diode to repair/ replace. Any suggestions to fix this?

 

First thing check would be the brake light switch.

 

thank you very much for the very detailed diode replacement instructions and where to find a fitting diode replacement!!