[marrymemercedes]

Hi,

I've got a 2010 E91 and I'm tracking down why my driver side reverse light doesn't work. My multimeter is showing that I'm not getting any power to it. (Black/violet wire). It looks like it had been stabbed with a multimeter prong previously so I traced the wires proximally and to my horror I wasn't the first person there.

I found this right where the wires enter the body from the tailgate:



and



Looks like both tail light wires were jumped. Problem being is I can't identify which one is right and which one is left. Further, having the issue so proximal doesn't leave me with a lot of room to clean this up. I was hesitant to pull on the wires to try for more length as I didn't want to cause more issues with clearly brittle as is wires.

How can I trace these wires further? I assume I have to take the interior roof panel down. I looked in the Bentley manual and couldn't find my answer. The remainder of the wires appear to be in good condition but I will check continuity before placing all the interior panels back on. Any help is greatly appreciated.

[Tambohamilton]

Looks like you'll need a repair harness...

[marrymemercedes]

Wow, thanks for the reply. Figured there must be something out there like this considering how common of an issue it seems to be. Definitely more involved than I was hoping for but oh well. I guess I'll find my credit card and get the harness! Thanks again

[Tambohamilton]

I have to do mine soon too...not looking forward to it. Like you say, it's a lot more involved than I'd like!

[Serf27]

Have you tried resetting the frm counters?

I had an e90 the other day where the right rear reverse and brake light didn’t work no matter what. Turned out a bulb shorted out in the housing and cut the power off to it.

[marrymemercedes]

Thanks! I’d like to try resetting the FRM. Unfortunately I don’t yet have a cable or the program to do that. I think it’s definitely a worthwhile endeavor after some more reading. I have also disassembled the interior and the wires (other than right where they were repaired previously) look good. I’d like to check if the wire has continuity from the FRM to the tail light before I start hacking away further. I’m tempted to just do the harness now anyways as the interior is completely disassembled.

[Serf27]

I’m thinking the previous owner who had the work done, found some faulty wires, had them repaired and still had no power to the lights, because of the frm.

[gee4711]

FRM could be dead (hardware broken) or just a software issue, perhaps you can find a coder he can test if it is only a software issue or if you need to replace the module.

[marrymemercedes]

Originally Posted by Serf27

Have you tried resetting the frm counters?

I had an e90 the other day where the right rear reverse and brake light didn’t work no matter what. Turned out a bulb shorted out in the housing and cut the power off to it.

Thread from the dead. I figured I'd bring this back up just for closure if anyone else stumbles on this. You were right. I reset the FRM counter using tool32 and it worked! Interestingly the counter had stopped at 14 instead of 50. Just another quirk of a used car with a questionable PO. Thanks!