F/Foglight issue, related to LKM?

[brendanm]

I have a 1990 BMW 535i, the error F/Foglight is always on, and the foglights don't function. I occasionally get a License light error as well, but the bulbs etc... are new so it should work fine.

I've taken the Foglights apart and the bulbs appear fine, I've tested the wiring with a volt meter and although there is a some signal there, it is quite weak. The plugs themselves look as though they need to be replaced, and I tried cleaning the contacts as they appeared to have some corrosion or oxidation build up.

But now I understand that the LKM may in fact be the issue. That the soldering on the circuit board has a tendency to go bad, and needs to be redone. Before I go out a completely replace the LKM, I would like to try and repair it, but I've looked at the pictures on the E34 website that describes how to repair it, and I can't deduce what I am supposed to do.

If anyone has experience in this area, suggestions on how to go about fixing the issue, and/or narrowing the field of potential problems, I'd greatly appreciate any assistance you might be able to offer me.

Thanks
B.

[brendanm]

Here some pics of the LKM from the E34 Website.

[DaveVoorhis]

I have experience in this area. The solder cracks on the solder pads for the relays. Re-solder them. I have circled the relays on the following pic:

http://shark.armchair.mb.ca/~dave/BMW/LKM.jpg

[shogun]

Some corrections to that info on Brunos site, I have already asked him to add my comments
http://www.bimmerboard.com/forums/posts/255204/

[SC David]

I had the same error come up with my car. Fog lights and connections were fine. I swapped LKM's with a local member to see if that was the issue, and all lights worked with his. So I bought a used one "in good condition" off ebay, which turned out not to work and the low beams wouldn't come on. So, with a spare LKM to toy with I did the soldering job on my old LKM and despite my lack of technical skill it was an easy job, and turned out fine. I followed the writeup on Bruno's site.

[brendanm]

Hey THanks

That's exactly what I needed to know. The doctored up graphic and instructions are gonna be a huge help. Are there any other issues I need to be aware of? For example, pulling the LKM out, does that reset or change anything? Any nasty consequences to botching the job?

Would a faulty LKM also explain why my License light error comes up on occasion? It seems to pop up every other time I open my trunk and shut it, obviously there's something wrong with the lights themselves, if they're sensitive to the opening and shutting of the trunk lid. Any suggestions there?

Thanks again guys.

B.

[Black 535i]

Check the wires from the rear seat to the trunklid for any breakages as well as this could be causing the fault errors.

[Elekta]

Check the wires from the rear seat to the trunklid for any breakages as well as this could be causing the fault errors.

actually check the wiring loom from the foglight back into the harness. I had a problem there with one of my fog lights. It would only work in the rain, so that was enough to have me check from the pigtail on back. It was a crusty and cracked insulation on a lead from the fog light. I went to a junk yard and made a pigtail from another foglight wire and away the problem went.

[compmore]

i to was getting similar messages and was told t was the lkm.replacing it didn't fix the problem.found in the archives some who had a similar problem and it was caused by the auto headlight adjusters

disconnected them and has been perfect since

geoffb

[shogun]

Would a faulty LKM also explain why my License light error comes up on occasion?
License plate is not controlled by the LKM, only low beam, high beam, fog light front, and non US spec. cars have a 4th relay in the LKm for rear fog lights.

Clean the licence plate bulb and connectors, often they are corroded.