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View Full Version : My E34 switches on her headlights all by herself.



Patrick Lemmens
02-28-2008, 05:08 PM
E34 december 1991, 525TDS , Belgium. 251.000 km

When driving the car or when she's parked (parking without key in ignition and car closed) my e34 switches on her front-lights (most outer headlights : not the parking-lights but the lights you use for driving at night) all by herself. The lights stay burning for 10 to 20 seconds and go out. Sometimes a few minutes later, other times an hour later (at random) she does it again and again... As long as she continues to start in the morning, there is no big problem. When she puts on her her headlights in the front, the red lights at the back don't burn !

Leaving the car with lights on, but removing the key, the headlights are automaticaly switched to parkinglights (this works as designed) and the lights at the back of the car also burn.

Has anyone any idea how to adress this item ?

Thx, Patrick

Tiger
02-28-2008, 06:00 PM
I would say it is your LKM that needs to be changed. I know this because I triggered the relays manually with cover off to test my LKM. Seems like your relay is shot or something else is triggering your LKM.

GS535i
02-28-2008, 06:20 PM
It may be possible that one of the 5 micro relays inside the LKM module is defective. This module ( ~ 200x80x25mm) is near the central electrical panel ... and is frequently the source of strange lighting issues.

Morgenster
02-29-2008, 02:54 AM
Die lichtkontrolemodule zit aan de rechterkant bij de motorcomputer. Da's een duur spulletje dus misschien kan je best bij een sloper zoeken naar een deftig werkende.

shogun
02-29-2008, 08:11 AM
as you have a Euuropean version, you also have a European version LKM.

Non U.S. LKM's and most of the japanese version LKM's have 4 relais, the additional one is for the rear fog lights.

If you open the LKM, and the connectors face down so that you can see the relais on the board, the order is from right to left side:
low beam headlights
high beam headlights
front fog lights
rear fog lights (NOT on U.S. version).
Here you can see the opened LKM.
http://www.bmwe34.net/e34main/maintenance/electrical/LKM.htm

U.S. headlights have only 3 relais,
1 for low beam headlights
1 for high beam headlights
1 for fog lights front

And the low beam headlight relay has 2 ON contacts!

Often one of these contacts does not work. Cleaning, resoldering helps.
Sometimes even bending the contact.

The LKM might look different from this pic, as there are various makers, it may have even 2 boards, but the function and the pins are the same.
The fuse for the low beam comes AFTER the LKM, so if the contacts are not there in the relais in the LKM, the fuse has no power. I know some people which have just soldered the 2 contacts for right and left together, but that is not the final solution.
And the headlight fuses comes after the LKM relais. So if the fuse is o.k. but there is no power, it is the relais inside the LKM.

LKM-L and LKM-B pin -out

1 High Beam stalk at steering wheel
2 terminal 30 (continious power)
3 switch low beam/dip light
4 data to CCM = check control module
5 data to CCM = check control module
6 F1 terminal R, IC supply
7 from k7 P2 - tail light right

8 tail light right
9 tail light left
10 parking light right
11 parking light left
12 from brake light switch

13 brake light left
14 switch licence plate light on
15 3rd brake light
16 fog light front left
17 F7 15A, terminal 30
18 fog light switch
19 rear fog light switch

20 high beam via fuse F13, F14
21 low beam left F10
22 low beam right F11
23 check via CCM + CC + OBC (check control module-check control-on board computer)
24 ground
25 data to CCM

26 from K7P6 tail light left
27 from K7P9 parking light right
28 from K7P5 parking light left
29 brake light right

30 licence plate right
31 licence plate left
32 fog light right, front
33 fog light right, rear
34 fog light left, rear
35 F8 15A for rear fog light

Note: this is the ECE/EU version, some pins might be missing in other versions. But the set - up will be the same. So for the US LKM probably the pins for rear fog light might not be there respect. not connected internally.
Depending on year of production and the makers of the LKM the internal parts look different, but the pins are always for the same function.

The pins in one row are 1 - 19
and the other row
20 - 35
-------------------------------------------------------------
Or my idea: open the LKM, remove the plastic cover and insert it again. Then push the contacts of the relais and see if they work. Switch on ignition when doing that.
http://www.bilder-speicher.de/07120803742843.gratis-foto-hosting-page.html