Brake, tail, number plate and dip light warning won't go away

[Unregistered]

Hi Lotus88,

I HAVE LIGHTS!!! YIPPEEEE...

Took car to garage, mechanic said that my car DOES NOT have an LKM module and that BMW are prone to doing such things.. Apparantly they 'hide' them in either the front left fusebox, the front right 'fusebox' (same opposite side), or the one in the rear under the seats.

Mine was fixed by the checking and repair of the boot wiring loom which was damaged (according to the mechanic, its a 'common enough thing') and he resoldered ANY joints he came across, cleaned up all the contacts (bulbs, relays etc) and hey presto it's all ok..

Hope this helps?

Cheers ppl,
Bob1004

[Unregistered]

Many thanks to Reidal, Damian and 530iTouring.

Mine is the left side Headlamp Levelling Motor. It's working perfectly, without grinding sound or whatsoever, and still in original sealed condition. Some time ago I did a service to the right side Leveling Motor, but it wasn't the cause in this case.

Now it's the 5th day it's disconnected, and NO single false alarms came on...

Just wondering, what's wrong with the Headlamp Levelling Motor that cause this very stupid false alarms ?

Eri.

[system11]

Hi Guys

The top score goes to Damian and Eri for highlighting the Headlight leveling motors (but thanks to every one else for their valuable input ).

I will now try and work out how apparently perfectly operational motors can cause the spurious warnings experienced. I suspect electrical noise is being fed back into the lighting circuits from the motor commutators.

This is exactly the problem my car currently has, although pulling the LKM and cleaning the contacts made half of the warnings go away. Did you ever resolve this fully?

[Reidal]

I have to admit to a degree of laziness on this as I have not sat down with scopes and meters yet (also been busy with Oil pumps and cam chains).

Just after I worked out that both leveling motors were causing the issue, I had to replace the battery.

Ah ha I thought , failing batteries often exhibit hi internal impedance which means the current drawn results in an increase voltage drop across the battery terminals (hence the failure under load).

This can also upset the batteries ability to act as a short circuit for electrical interference throughout the system which means the noise becomes more noticeable to things like OBC and sound systems.

Wrong Reconnected the leveling motors a couple of weeks ago and immediately the warnings popped up again.

So it's back to the drawing board. I'll try and do the scope and meter thing over the next few weeks before the weather here in Melbourne gets to good to do more than laze by the pool sipping a good glass of red.

[ewidjaja]

I got the idea that the Leveling Motor cause the problem from this thread back last year. From that time, I just remove the Left side Leveling Motor connector from its wires.

Last weekend, still wanting to know what causes the various Light Failure Warning false alarms...

I decided to open (literally) up the Leveling Motor assembly. I carefully pry it open (hammering using small (-) screwdriver). After it's open, I see the motor, and a small PCB (printed circuit board). And, aha..... there is a tiny electrolyte capacitor rated 33 uF / 25 V / 125 C. I think it might be the problem, faulty capacitor can fail to filter unwanted noise from the motor itself. But I don't have the same capacitor rating. So, I decided to solder it out, and replace with whatever I had (100 uF / 16V / 85 C). Then I reassemble the pieces and glue both clam shells of the Leveling Motor to ensure it's water tight.

After putting in everything together and connect it to the connector, then try to run the engine and turn all lights and equipments on... and the false alarms just vanish......


Eri.
just very happy to save my Headlight Leveling Motor

[Elekta]

Did you take pictures of this endeavor? I too would like to restore my headlight leveling motors.

I finally disco'd the motors after replacing the two touring rear wiring harness year and a half ago.

[Reidal]

Well done Eri.

I may look at doing this as well now that you have given us the lead.

If you have not got photos' let me know and I will make sure I document the process when I do it.

[ewidjaja]

Sorry Reidal and 530Touring,


I didn't take any photos.... But it's straightforward.

1st you need to take out the Headlight Leveling Motor (I think you must know how to do it).

Then you look at how 2 plastic shells joined together along the Leveling MOtor body. I pried this line using a tiny (-) screwdriver hammerred into it. Be careful in doing this so not to break the plastic shells.

After they are apart, carefully open it, and see only 1 electrolyte Capacitor soldered in the PCB. Desolder it, and change with new one. Be careful in changing Electrolyte Capacitor because they have different pole (+ and -) and don't put the new in wrongly.

After that, reassemble everything, and put some glue (I use 5 minutes Epoxy adhesives, the one coming with 2 tube -- Epoxy and Hardener -- and we need to mix together and it will harden in 5 minutes) to make sure the join is watertight. Oh yes, when gluing it, I tie both plastic shells with a tiny nylon to make sure the join is tight.

Good luck... And share how you are doing.


Eri.

[NJHokie]

Does only the tourings have headlight leveling motors or the sedans as well? I have a 91 535i and i'm experiencing the exact same problems.

[wingman]

On my car, for some unknown reason, the wiring loom was cut where it passed through the metal wall behind the back seat to underneath the back seat. It was my reversing lights that were intermitently coming on then off. With to boot/trunk lid closed the lights worked but when I opened it it tugged on the wiring loom and split the reversing light wire under the back seat. I know this sounds odd because the wiring loom is attached at the hinge and in other places, but it can still move. My car is an '89 525i - on cars with battery under seat, the wiring loom will come through right behind the battery - I suppose.

Phil

Phil,
This is an old post I know but was this problem causing your 'lic.plate.light' warning to come on? I've had the lic plate lights coming on when opening the boot for a while now but now I'm getting a dash warning. I've changed the globes to no avail.