Thanks. Added to DIY sticky.

 

Glad to contribute! I hope it saves someone some hassle.

 

Brilliant Repair!!! Saved me a huge headache with my e39 525i wagon that had been plaguing me for a while! Had no instrument cluster lights, random blinkers and headlights, etc... followed your lead and everything works perfect now - if you were nearby I'd buy you a beer or 3!!

Thanks Heaps!!!

 

I'm planning to apply an acrylic or silicone conformal coating on the pcb after cleaning to further bulletproof the circuits. thanks for the write up

 

WOW, can't believe that actually worked out!!!!! Thank you

 

I 'fixed' my faulty LCM3 in my 2000 M5 by cleaning it. My high beams would turn on with the left turn signal, unless I had the headlight switch to 'off' or 'park lights' and the stalk pushed forward to 'high beams'. After a few days, they started coming on with the key in the 'on' position no matter what position the headlight switch was in. There was a small amount of corrosion on 3 places on the rear of the PCB. Cleaning the corrosion fixed all problems.


Here is how I cleaned it:

Tools:

• panel remover
• 8mm nut driver
• toothbrush
• >70% isopropyl alcohol

See here for LCM removal/reinstall instructions.

1. on the tapered end cap opposite the plugs, pry the tabs open and lever the end cap off
2. All plugs are attached to the PCB, to get them through the case and slide the PCB out:
3. pinch the white or black end plug in the middle of the long axis so the sides go in enough to allow the small tabs to no block it pushing into the case
4. lever the 2 small tabs on each end of the center plug and push in on the plug. I used my panel remover for this, but a flathead screwdriver should be just as good
5. pinch the other end plug and push on the end plugs and pull on the case in order to slide the PCB out. it takes a bit of force
6. look at the front and especially the rear of the PCB for any amount of corrosion. You can see from the attached photos that the corrosion on mine was pretty small, but that's all it took. If there is no visible corrosion, might as well clean it anyway and see if it helps because it's only a few extra minutes at this point and might save you the hassle of buying/coding an LCM.
7. pour some alcohol on the PCB and gently scrub with the toothbrush. Be sure to scrub in all directions so you get down into the nooks between chips and solder points.
8. dry the PCB in front of a fan
9. before reinstalling PCB into case, connect to car and see if you fixed it. Mine said 'lights on' in german the first time I keyed the ignition. After an on/off cycle it changed back to english and all problems were gone.
10. PCB installs back into the LCM case by just pushing everything back into position and it will all click back into place
11. plug connectors in, reinstall LCM and trim panels
12. profit

Hi. Many thanks for this. I am having issues trying to remove the PCB from the LCM casing. Appreciate you posted this a few years ago(!), but would appreciate any further help on this matter. Just out of interest, if you are based in UK, would be great if possible we can catch up and I can bring the part to you? Many thanks.

 

TY! Had a problem with turn signals going crazy and rear running lights staying on killing the battery at night. removed lcm, cleaned all 3 plugs and motherboard. black plug had corrosion. after cleaning everthing is working properly. cost $6 USD to repair.

 

THANK YOU!! My LCM was acting up very badly. Followed these steps and now it works as if new. Thank you again. Saved me money and headache