Xenon Headlights 'Auto Adjusting' too low whilst driving...

[EdButler]

Hey All, im reaching out to all the techies here!

Very recently ive noticed that my Xenons are adjusting themselves incorrectly whilst driving. After the car is left for a while, they are excellent and throw light beautifully down the road (as usual, and as id expect). However after a few minutes of driving, they angle much MUCH lower down and light only ~1.5-2 car lengths in front.

Now i know this isnt a simple adjustment issue as the car hast been touched, never had an accident and both lights are still aligned with each other. This is starting to make me think that it is on of the Auto-Levelling sensors failing (maybe making the lights low as some kind of safe-mode?)

Does anyone have any clue as to where i could start to look??

Many Thanks in anticipation, Ed

 

[EdButler]

Right ill start looking at the adjuster arms here:
http://www.realoem.com/bmw/showparts.do?model=BT52&mospid=47797&btnr=31_0644&hg=31&fg=05

UPDATE:
Just checked the little arms on the sensors and parts 5 and 10 on the diagram (the vertical bars that connect to the wishbones) and they both seem fine. I looked at these as there is a mention of them snapping on the E46 Bimmerforums FAQ.

Now does anyone have any fault finding tools near the Sheffield area to try to identify a faulty sensor?!

 

[cj10jeeper]

Well Ed you went straight for the sensors and that would have been my first port of call given that both lights are performing in the same manner. I guess though that just because they are in one piece does not mean they are functioning correctly. The other point would be a fault in the LCM. Never heard of it but l'd agree with you about dropping to some sort of fail safe 'low' option.

It's unusual that you describe them as sinking after a few minutes. Can you see this against a garage door or wall that they have dipped and not an illusion?

I'd get it on a reader and see if there are any codes being thrown.

 

[EdButler]

Cheers Phil, its definitely not an illusion, the difference is night and day! Driving on the Snake Pass is becoming somewhat hairy late at night!! Even the main beam is now rubbish

Will start asking friends for OBD2 tools to see if its indeed a sensor that has died... I hope so as the prospect of changing the LCM doesnt sound too healthy on my wallet!

 

[cj10jeeper]

Ed - it might be worth undoing a single bolt on the 2 sensors one at a time and operating them gently to see if the lights raise or dip in response. You could test it by jacking the car from the centre rear and then both sides at the front as an alternative. Not very high tech but the lights should react.

LCM are a couple of hundred pounds and need coding. IIRC if you swap them out, drive a few miles and don't code they can throw a mileage tamper error as it's one of the places that mileage is stored. That said I did do a static test switch with another 3.0i in my drive with no ill effects while setting up his xenon lights.

 

[EdButler]

Awesome little bit of advice mate, never thought of that Will have a fiddle one night (Hurrayy ive found probably the only job that benefits from early winter nights!!)

Thanks for the heads-up on the LCM - not the road i wanna go down to be honest, but we shall see