Lighting issues: LCM / Cluster?

[WJord1]

Hi all, I have a 2005 4.8iS and currently experiencing some issues.

Previously I noticed some water in the passenger footwell and found the sunroof drain was blocked. As a consequence of this I then noticed issues with the lighting. At first, my third brake light would permanently stay on (with engine off) and indicators/fog lights etc. would not display on the cluster but work perfectly from the outside. Now the brake light doesn’t stay on.

I determined it was an LCM issue and found a replacement used part with identical part numbers. After getting this coded in to remove the tamper dot, I found the indicators etc now illuminate on the cluster, however the third brake light is always illuminated and the drivers side front indicator stays illuminated permanently.

I’m not very electronically minded, so any next steps on what to check would be great. Given I have different issues when swapping the LCM, I’m not sure if this indicates I’ve bought a faulty replacement LCM or if the issue could be with any of the plugs/wires to the LCM or something completely different.

Any help is much appreciated!

Thanks,
Will

[WJord1]

To add to the above. I have previously changed the brake light switch, and the clock spring with no avail.

When the replacement LCM was coded, no other faults appeared (apart from an airbag fault which I believe was when the door handle carrier was replaced, it was cleared and no faults now present).

[Alan Gunn]

Might want to get it scanned again.
Never had this problem and the only time an indicator has stayed lit was when a side-light bulb was out but that would show on the dash.

[Greydog]

OK so you have had the LCM changed and Coded near the LCM is an Earth point with multiple connections. As you suffered water ingress the Earth point could be compromised it needs taking off and cleaning thoroughly. I had a lot of difficult to trace issues with my E53 4.6 BMW love these common earth points I worked my way through all the earth points cleaning and remounting with electrical contact paste all mystery issues went away.
As Alan says if you haven't got a scanner get the car scanned again but look for any units greyed out (can't be seen/communicated with)

Good Luck finding the fault
Dave

[WJord1]

Thanks Alan & Dave, appreciate your responses.

I think I’ll go ahead and get it scanned again.

Dave, with regards to the earth points, as mentioned I’m not too clued up with electronics. What specifically am I looking for? I’ve checked behind the glovebox for any signs of damage / water stains and there’s plenty of electrical gubbins going on, how would I know where the ground point is?

Thanks,
Will

[X5Sport]

Ground points are all on the chassis/body itself and have brown wires going to and from them.

[Greydog]

The earth point is on the side of the footwell where the LCM is mounted, it looks like a Comb with a single bolt mount to the chassis. As X5sport says it will have a bunch of Brown wires attached.
I cleaned all the connections including the mounting to the chassis, if your "new" LCM was a used item make absolutely sure it is correct and undamaged it may be worth talking to one of the repair specialists like BBA Reman, ECU Testing or Cartronix

Fingers crossed you get it sorted
Dave

[WJord1]

Thank you X5Sport & Dave, again I really appreciate your responses.

I’ll go ahead and check the ground points when I’ve got some time and see if it makes any difference. If not, sounds like next step would be to get another diagnostics check to see if there are any greyed out modules. If still nothing I’ll send off the spare LCM for checks/refurbishment.

Thanks again. I’ll report back with progress.

Cheers,
Will