1st Gen R53 Cooper S Most liked posts in thread: Ignition Switch causing Brake Light Issues?

Nope you can't do it. The BCM needs to be coded to your car keys and everything else.

I know Mike at Helix can do it if you are near Philly, PA.

FYI we call anything West of Lancaster, PA BFE. :lol:

Please check all your grounds especially the one under the hood by the upper motor mount. Check both ends and make sure they are clean and tight. Next have your battery tested or replace it with an Optima RedTop 34R. ($150-$200)

All of these things are better then buying a BCM for $400 + install and programming at a dealer.

 

And your battery is in "Good" shape?...
When they start getting weak, strange things happen...

You have a 2003 S and a 2005 S as well?

 

Let us know how old the battery is.

 

^^^^ all of this,


except the part about the Optima.......

 

The brake lights are not connected to the ignition switch, so the ignition itself is not the direct cause. However, it controls power to various modules and you may be seeing an indirect effect.

All 3 brake lights are driven directly by the BCM (Body Control Module) in the passenger footwell. The brake lights are not driven by switches and relays, but directly by electronics in the BCM. Even the brake pedal switch merely sends a signal to the BCM, which actually controls the lights.

Have you checked the switch at the brake pedal? However, I can't think of how a malfunctioning switch would cause the symptoms you describe. Your BCM might be going bad. By any chance, do you have the "rear fog mod" that makes the rear fogs operate as an extra set of brake lights? There is evidence that this mod can cause the BCM to fail prematurely.

 

If doing the rear fog mod, it's a good idea to use LED lights in the fog position for
this reason. This results in a minimal increase in current rather than doubling it.

 

I' guessing yes....just guessing, but would make sense... one way the dsc would intervene would be brake application...
The dsc might be seeing the brake lights on...saying brakes on? and faulting cause it has determined the signal to be false...so the dsc faults, since it has a signal coming in that it knows is false....
Back when I had a t-map/map fail, the dsc came on...guessing it was a similar fault with the computer seeing data that was unreliable....
Just a guess...but I'm thinking the dsc is a symptom....

 

WOW....

I have an 09 and it just turned 24,000 miles... I'm doing something wrong...:cryin:

 

New OEM BCM = $ 410.00 for just the part before programming.

 

Ouch !! You definitely want to be sure that you need that part.