E34 OBC Errors - Tail, Lisc Plate, Dip Beam, Brake - SOLVED

[roo 41]

Hi team

Having a few off errors pop up on my OBC - 1994 E34. First of all - all lights/fogs/brakes are working perfectly.

When driving around with my lights off, nothing pops up. As soon as I turn my lights on I get the following errors:

DIP BEAM

TAIL LIGHT

LISC. PLATE LIGHT

and then as soon as I brake I also get:

BRAKE LIGHT

None of these show up unless the lights are on. So it has to be some weird wiring thing. I have read a few different explanations/fixes:

Rear boot wiring loom - Would this effect dip beam also?

Re-solder/replace LKM - Anyone done this?

Unplug headlight motors - Would this effect tail/lisc/brake lights?

Any ideas?

Thanks!

Edited August 4, 2014 by roo

[lord_jagganath 421]

I get these too, I have put them down as the wiring loom needing error/contact checks.

[Phil-540i 166]

I get same, spasmodically depending on how she is feeling at the time. Like you Roo, all bulbs are fine, so I'm not going to chase it too much at this stage. When lights get turned on, its like it sorta does a 'self-check' on the system (note to self - must get around to reading owner's manual one day!!)

In terms of fault codes relating to lighting coming up on the OBC - my research seems to indicate if bulbs are ok, then highly likely 'fault code' is being tripped due to earthing gremlins within that circuitry.......

Mine passes wofs no hassles re lights, so its just another of her 'quirks' I reckon........

[roo 41]

It's a super annoying quirk though as I can't use the OBC for clock, fuel consumption, range etc while they are all showing up.

A lot of people put it down to headlight adjusters so will unplug those and see if it fixes it. Will also inspect boot hinge wiring tonight.

[Phil-540i 166]

Ditto - mines same while its 'self checking' or showing a fault or whatever - does yours not 'clear' after 30 secs or so, leaving OBC free for clock readings etc?? Took me ages before I learnt that OBC display can be replicated & shown in dash area itself too.......

[roo 41]

No it doesn't, not when the brake light one comes up. Obviously deems this is as more important than the clock etc which it is. Am aware I can have the same details showing next to the radio, would like both working properly though.

[antil33t 90]

Faulty CCM/ LKM

http://www.bmwe34.net/E34main/Maintenance/Electrical/LKM.htm

If you really want your OBC to work and not care about the check system remove the check module from the e-box under the bonnet, and you'll get a "check control" error every time you start the car instead.

[roo 41]

Seems like quite a common problem. People who have replaced the LKM actually had their lights stop working. Sounds like just the warnings could be wiring/headlight adjusters etc.

CCM is a good idea. Will ingestive these options tonight.

[BM WORLD 1283]

also the headlight adjuster motors , fail and they cause alsorts of faults to come up , try unpluging them .

[kiwi535 538]

brake light(or is it brake lt (elec) can be brake light switch,or maybe the centre hight stop light.

License plate can be the boot hing wiring

LKM resoldering is the fix for when you lights sometimes randomly dont work or go out

look here

http://www.bmwe34.net/

they all common E34 problems

can also get obc errors when using different brand bulbs and or one light is about to blow.I used to replace bulbs in pairs and keep the other one for a spare

Edited October 8, 2013 by kiwi535

[roo 41]

Update - Had a play after work. Loom going up the boot hinge had worn through its fabric sheath and could see the wires but none of the actual wires were exposed. I taped this up.

Headlight adjuster motors were a bit more tricky. I can't get either of the clips/plus off. They are really close to one of the bulb holders which makes it tricky (yes I was pushing the tabs out) and I didn't want to pull too hard as the motors don't look all the sturdy to be tugging off. Any tips for getting these plugs off?

[roo 41]

Bump, any more advice people? How can I correctly diagnose what is causing the problem? Is there a way to test the rear boot wiring? It's super annoying have this pop up every time the lights are on. All headlights and foglights are the same brand/type of bulb so it's nothing like that. Will try again to unplug the headlight adjusters but don't want to break 20 year old brittle plastic. Is there a way I can test the CCM?

[Eagle 1662]

Can't really avoid breaking tabs as they are just too old I wouldn't as they plug in fine and are secure without them, you can always get new plugs if you wanted.

Easiest method is by swapping in a known good CCM and LKM modules

[BM WORLD 1283]

unplug the head light adjusters , then see if the faults go away

9 times out of 10 they do .

[roo 41]

Finally got around to unplugging the headlight adjusters (after 3 lots of CRC and skinned knuckles) and no more errors! Thanks Brent & co.

[BM WORLD 1283]

no problem , enjoy