Brake lights won't go out

C

cj10jeeper

Lifer
 Lichfield, England
Odd one this and as it says - brake lights won't go out.

Start the car and all 3 come (both sides and centre) on and stay on.
Dash shows the yellow bulb error message.

Nothing obvious with the pedal. Had the battery off for 15 mins and reconnected, but no change.

Currently running diagnostic programme on all the modules and will clear errors if I find any.

Anyone come across this or similar that might hold clues to the reason??
 
Weird. Assume you have checked the fuse ? Wouldn't put it past BMW to have snuck in a "safety feature" that turns all the brake lights on if a fuse fails. Makes no sense, but then again if you lose a sidelight then the indicator on that side lights up when your lights are on till the sidelight is replaced IIRC. That makes no sense either... :roll:
 
Unsure of the setup. But is there a micro-switch on the brake pedal? If so could this be jammed or broken? Can you unplug it if so do the lights go out?
 
Nothing in the errors that I can clear.
Batteries good and had it on a charger anyways just in case.
No fuses out but can't see why that would trigger the lights on.
Earth - I'd expect one side or something not so symetrical.

I'm thinking module like the LCM playing tricks.

Worryingly looks like a trip to the stealer to sort it out as no way will my indy specialist have any knowledge of this sort of thing.
 
Interesting Rich. He had no cruise control and I've lost MFSW control of radio, etc. Everything else id just fine.

That makes me think electronic issue tripping the lights on.

Hope mine sorts out by morning :)

Mark-Z4 theres a panel blocking access to the pedal switch so that will have to wait until morning to drop it and take a peek. Easy enough to do with just 3 self tappers.
 
cj10jeeper said:
Interesting Rich. He had no cruise control and I've lost MFSW control of radio, etc. Everything else id just fine.

That makes me think electronic issue tripping the lights on.
Click to expand...

Or perhaps lights on stopping control of radio? I wonder if MFSW control of radio is present on my car whilst braking and the microswitch is lighting the brake lights. I don't use the Zed every day but will try that next time it's out.
 
OK so the canbus thinks bulb out and therefore showing dash light. This means your rear brake light circuit looks open to the canbus and must be shorting on from a more local switch or wiring fault. I would definitely undo the full circle mod to eliminate it as a starting point.

Aaarrgghhh! I hate not understanding why things go wrong!
 
Well due to lack of time she's in the dealership to diagnose and fix. Quoted 48 to 72 hours turnaround.
We shall see what they make if such a modified car :)
 
Well it was indeed the brake switch. Internal failure on it, meant it caused lights to remain on.
Unrelated error of blown fuse at same time took the MF steering wheel switches out.

Bad news is the switch is £74 plus fitting, so as I have no time and if they mis diagnosed the cause, etc. I'm letting the dealer fit it and get it back tomorrow.

Thanks for inputs and ideas.
 
I just knew there was a fuse out somewhere :wink: :P

Glad it's something simple & getting sorted :thumbsup:
 
I knew there was a fuse out somewhere :wink: :P

Glad it's a simple issue to get fixed :thumbsup:
 
Had the same problem, brake lights on and no cruise control. Turns out it was a micro switch on the brake pedal. Easy to replace once you twist your body around to see it under the dash. Forgot the cost, but it wasn't much and took maybe 10 minutes to replace. Was on my 2003 Z4 2.5i.
 
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