<E34> Headlight Problem

[ingraham@xxxxxxxxxxxxxxxx (Curtis A. Ingraham)]

In BMW Digest v09.n1229 Ted Goodman <Ted@domain.elided>
wrote:

> I'm from UK. Saw your list whilst looking for BMW help on a problem 
> with my E34 525 ... The problem is that for no apparent reason, my 
> dipped headlight beams go out and sometimes stay out: What I have 
> noticed:
> 
> a) Sometimes related to a rough road, as if its a loose conenction
> b) Other times not related. Smooth road and just goes out.
> c) Circumstances in which it comes back on are just as varied.
> d) Sometimes seems heat-related. Warm engine, warm weather seems 
>    to worsen the frequency of lights going out. Other times 	not.
> e) No obvious loose connections, although opening the fusebox, there 
>    are two large black boxes (as opposed to the coloured relays). 
>    One is, I have been told, the checking system circuits. Tapping 
>    the other sometimes affects whether lights are  on or off.
> f) Some days works well all day, other days constantly going off or 
>    staying off.
> ...
> Ted Goodman
> Wolverhampton UK

The problem is likely in the Lamp Control Module (LCM), one of the 
large black boxes you saw in the fuse box under the bonnet.  The LCM 
is the largest plug-in relay-like thing in the fuse box.  The currents 
for most of the exterior lights flow through the LCM.  

It is common for solder joint problems to develop in the LCM, and 
solder joint problems can have time/temperature/vibration 
characteristics like those you described.  A replacement LCM is 
rather expensive, but a competent solderer can probably repair 
yours by resoldering all the connections.  Unplug the LCM from 
the fuse box, carefully remove the LCM case, resolder, reassemble, 
and reinstall.  I cured a similar dipped beam headlight problem 
that way on an E34.

Curt Ingraham
'72 2002tii
Oakland, California
2002 Radiator Upgrades

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