4 series convertible rear light issue

[KeithE]

Had a warning on the dash to say a brake light had failed which subsequently cleared itself. This was followed by notification of an indicator failure in the same cluster which again cleared itself. Having now had a chance to investigate neither has actually failed however there is an intermittent failure in the wiring to the cluster whereby the entire cluster dies.

Although I can't see any damage I think the failure is in the cabling rather than the connector but I have given it a clean and a quick spray just in case.

Has anyone else seen this in any of the F30 series?

[Olivergt]

Not in an F30, but previous BMW's E46's and E32's for example, were prone to throwing bulb warnings when nothing was wrong.

From my understanding these are caused by poor connections where the bulbs go in, so it might be worth taking the cluster out again and removing/cleaning all the bulb connections.

I have a side light warning on mine but the light is working, I haven't had a chance to take the bulb out and clean up yet though.

[KeithE]

I did check that but as it appears the whole cluster (i.e. tail, brake and indicator) all fail and comeback together I think it is probably the earth to the cluster rather than any individual bulb or connector - particularly as the tail is led

[McGee_22]

I haven't seen this (we have a 435d Cab) but a quick google reveals you need to locate the FEM (Front Electronic Module) and REM (Rear Electronic Module) and make sure there is no damp or damage near them. Between the FEM and REM they control and report on windows, doors, lights, PDC and more.

This tells you where the FEM is and what it does...

https://bimmerscan.com/bmw-front-electronic-module...

And this might tell you where the REM is...

https://f30.bimmerpost.com/forums/showpost.php?p=1...

And this thread contains similar symptoms...

https://f30.bimmerpost.com/forums/showthread.php?t...

F33 Cabs are notorious for leaking, filling cavities and then the modules in them with water.

Good luck.

[KeithE]

McGee_22 said:

Good luck.

Thanks, it looks like I may need it.

As you say the 4's are notorious for the collection of water where it shouldn't be. I had to replace the offside rear window mechanism last year as water had collected in the rear quarter (a common issue) and eaten the winders. The problem with that one is you can't get the trims out with the roof up and the roof won't go down with the windows fully up. It took ages to work a fix to get the roof to think the windows were dropped enough to drop the roof!!!!

[McGee_22]

KeithE said:

Thanks, it looks like I may need it.

As you say the 4's are notorious for the collection of water where it shouldn't be. I had to replace the offside rear window mechanism last year as water had collected in the rear quarter (a common issue) and eaten the winders. The problem with that one is you can't get the trims out with the roof up and the roof won't go down with the windows fully up. It took ages to work a fix to get the roof to think the windows were dropped enough to drop the roof!!!!

We had the exact same problem with the nearside rear window winder - the drain holes get blocked and the space fills with water buggering the motor. I claimed it under warranty and after some 'discussion' BMW UK agreed to cover it, as well as a 'fix' of enlarging the drain holes either side.