W203 Bi-Xenons no longer self levelling and too high

[c270_w203]

Hi there, my factory-fit Bi-Xenon headlights have BOTH stopped auto-levelling at startup and are aiming too high, making me really popular with oncoming traffic They also appear to flicker (not on and off) but more as if they're bouncing at the top limit.

I did have some recent work done on the suspension with all control arms replaced and the drop links too, together with the rear springs replaced but this was all done to pass an MoT, which it since did so I'm sure the lights were self levelling still after that work was done and the lights were obviously good to pass the MoT (with no advisories too )..

I've checked both the front and rear headlight level sensors on the anti-roll bars and they seem intact and correctly positioned. (see pics). I've also checked the 7.5 Amp fuse #51 and that's fine..


I've sprayed the links with WD40 and the electrical plugs with an electrical cleaner spray (Servisol IPA 170) to no avail..

The battery has not been disconnected AFAIK and there's no EML on..

Have seen other posts that conclude the lights will fall low if the sensors fail, but mine's the opposite and it's both lights..

Any other ideas I can check as a non-expert or are we talking about a trip to dealer to see what STAR says ? Is it possibly a SAM relay etc ??

It may seem like I'm an expert, but just did lots of research on here and other forums before posting so as not to waste you clever lots time.

 

[andy27168]

Hi,
You have done all the right things to check, Its sounds like its either one of the sensors on the suspension has gone U/S, or possibly the levelling ECU. This is of course provided that the sensors were replaced correctly when the suspension work was done, and as you say the fact that it passed the MOT the headlights must of been aligned ok.
I think you will need to get a diagnostic on the system, you should,nt have to go to a main dealers, try an independant far cheaper.

 

[c270_w203]

Thanks Andy, I don't think either sensor was actually removed during the work to be honest and the front bracket that fits to the anti-roll bar appears not have been moved at all (it's a 2003, doesn't look as though it's ever been moved).. Levelling ECU, ah I didn't realise there was a dedicated one.. ! Cheers again.

 

[spike60]

Is it possible for the linkage on the top pic to go the wrong way if the suspension has been extended? Could the black plastic arm point to the right instead of the left? Unrelated to MB we have some thing similar at work that if the linkage is pulled straight in unusual conditions it can then go over centre when the vehicle settles back down putting the linkage 90 degrees out. Just a thought. My MOT tester didn't even check the beam after I repaired my linkage!

 

[c270_w203]

Is it possible for the linkage on the top pic to go the wrong way if the suspension has been extended? Could the black plastic arm point to the right instead of the left? Unrelated to MB we have some thing similar at work that if the linkage is pulled straight in unusual conditions it can then go over centre when the vehicle settles back down putting the linkage 90 degrees out. Just a thought. My MOT tester didn't even check the beam after I repaired my linkage!

Actually that's a really good point - I suspect the anti roll bar may have been removed to facilitate the fitting of the replacement control arms so guess it could have been put back the wrong way or maybe a deep pothole may have turned it 90 degrees as you say - I'll try to find some pics of the correct fitting.. The control arms weren't picked up on an earlier MoT by the way, it was a routine service - so I had them done before the MoT so guess the tester would have done the lights rather than skipped them if it were a re-test

 

[spike60]

My Clk has different suspension but the levelling potentiometer(?) looks the same, on mine the black arm is pretty much lined up with plug and wiring, about 90 degrees away from yours in the pic. My memory isn't that good so I've just had a look!

 

[renault12ts]

I agree with the above...the diagram shows the arm forward not back as in the photo.

Good call Spike60.

 

[c270_w203]

My Clk has different suspension but the levelling potentiometer(?) looks the same, on mine the black arm is pretty much lined up with plug and wiring, about 90 degrees away from yours in the pic. My memory isn't that good so I've just had a look!

Crikey, cheers mate for going to have a look, appreciate it ! In the meantime I've also found this link (an extract from WIS I think) which also says it should be 90 degrees like yours. I'll be changing it over in the morning and will let you know how it goes. At least I smothered it in loads of WD40 earlier to free up the nut Thanks again for the tip off ;-)

 

[spike60]

Go easy on it, the nuts on mine were seized solid, the potentiometer is expensive and I was told a new one needs calibrating on Star. The linkage with the ball joints on is available separately for about £25. My problem was a bit easier to identify, -it was all dangling by wires!

 

[c270_w203]

Go easy on it, the nuts on mine were seized solid, the potentiometer is expensive and I was told a new one needs calibrating on Star. The linkage with the ball joints on is available separately for about £25. My problem was a bit easier to identify, -it was all dangling by wires!

Cheers, yeah will do - it looks pretty rusty - guess it will be a challenge after 9 years impact driver deffo out of the question. I'm actually wondering if I could do it by unbolting the potentiometer instead of the elbow link or if it doesn't look as though it's going well, might think about dropping the anti roll bar fingers x'd

 

[spike60]

On mine it had threaded steel sleeves moulded into the plastic body to mount it, these had corroded and split the plastic body at 12 years old. If you can do it without touching the potentiometer I would, from memory the potentiometer was about £130 and my local indy wants £72 to get Star out so mine is now Araldited into place!

 

[c270_w203]

Update - have tried to unbolt it at the elbow joint but the nut is just turning the bolt with it and there's no head to the bolt to grip. I've also tried to undo the bottom U clamp but this is also stuck fast. Looks like it may be off to my local indy to get it up on a ramp and possibly lower the anti roll bar :-(

 

[c270_w203]

Found the time this weekend to drop the anti-roll bar and reset the sensor arm position. It is now pointing the correct way ( > instead of < ). Unfortunately it has not resolved the problem. I wonder if something has happened because the sensor arm was incorrectly positioned previously. Does anyone know if for example there's a screw drive on the headlight which may have wound past the end of it's thread and now won't wind back ? If so, any tips / instructions on how I wind it back ?? Any other ideas as I'd really like not to have to resort to a session with STAR :-0

 

[spike60]

When my sensor was adrift but plugged in you could power the lights up and down by moving the arm with the ignition and lights on but I don't know if it reached the end of their range. I would expect to hear some noise from the lamps if it was trying and failing to move them.

 

[c270_w203]

Resolved (eventually !)

Hi all, thought I'd update this post with how this eventually got resolved..

Took the the car to an indy Merc specialist who weren't able to reset the lights using STAR. After some head scratching, they realised I had both front suspension springs broken - not just the tail end either - a full coil. I really didn't know and couldn't tell..

They quoted me another small fortune to replace the springs, so I declined and had them done at my local garage (ran by a friend). I then took the car back to the specialist to have the lights reset by STAR but they were still unable to do it. They then noticed that the lights had wound off past the end of the rods inside the headlight unit and were loose (possibly because the springs had dropped the front of the car so much, the sensors had done all they could to compensate)

They said they'd need to remove the front bumper and lights (another 3 hours labour) just to investigate, let alone resolve the issue so I declined again and back to my mate's garage. Thankfully, knowing the issue was within the loose adjustment within the lights, they were able to manually wind them back on to the end of the shafts and level them - no bumper removal required - an hour's work to fix the issue

All sorted and passed the MoT and I no longer get flashed

Thanks everyone for your helpful tips and ideas - what would we do without you !

 

[RWDpetrol]

I have a c63 and the xenons self level on startup. However, as I crawl up a ramp I don't see them continually self levelling. My BMWs' used to. Are the Merc's just not as sensitive?