Xenon Healdight Self Levelling Problems

[Tom131]

Hi Folks,

I'm hoping for some assistance with a weird little fault with my self levelling Xenons.

I Purchased this car back in the summer, when the long days meant that headlights were not a primary concern for me. On the couple of occasions I did drive it at night however, it was pretty obvious that something was amiss with the headlights. I quickly discovered that both of the levelling sensors were U/S (one was missing all together), but it was a relatively easy job to order up some new ones and get the system up and running again. Once functional I realised that the previous owner had obviously tried to compensate for the lack of self-levelling by manually adjusting the lights up as far as possible. Consequently, once they started working again, they were pointing pretty much into space, so I had to adjust them back to something sensible.

All appeared well until the end of the summer, when, due to a combination of shortening days and a significant change in work patterns, I started to do an awful lot more night-time driving. I still didn't feel the lights were great, and given the age of the car, I decided she was probably about due for a new set of (premium brand) Xenon burners. Fitting the new burners went without a hitch and the lights now seemed noticeably improved.

However, couple of days later I had to do a longer night-time drive, which necessitated a couple of stops en-route. The first stop was only a splash-and-dash, but when I got back in the car I found the headlights would not move up from the fully down position. I assumed one of the sensors had failed and had to drive on through the night with the marginal lights. A couple of hours later I had to stop again, this time for something to eat. After leaving the car for some 20-30 mins, when I came to set off again I was delighted to find that the lights had continued working as normal.

Over the course of the last few weeks, this has become a fairly familiar pattern. At first I assumed it was an intermittent fault with one of the sensors, or possibly a short, or chaffed wire. However, I have now realised that there is a very definite pattern with it. They will work first time, every time, at the start of a journey, but a short stop will always cause them to fail. If the stop is longer - say 20-30 minutes, they will be ok. In short, they are not working when hot. I've checked all the wiring and both sensors and I am as sure as it is possible to be, that neither are at fault.

Now, I cannot be certain that this only started after changing the burners, but that is certainly when I first noticed the issue. Before that time I was driving the car fairly infrequently, for short trips only and rarely at night, so it is possible that it has always been that way. However, it could, I suppose, be related to the fitment of the new burners, or the removal of the lights in order to achieve this. It is also worthy of note that the problem affects both lights - either both lights self-level correctly, or neither do.

So, what is going on? I can't seem to find any mention of a similar snag elsewhere on the forum, but I'm hoping someone may be able to help.

Could this be due to overheating from the new burners? Could this in someway cause the levelling motors to jam?

Are the lights even able to level independently? If one light developed a mechanical fault, would it effect the other one too, or am I looking for something which is common to both?

Does the light switch / light control module feature any relays? It kind of feels like a sticking relay, which is releasing after its had a chance to cool down - is there anything like that in the system? Could it be worth swapping in another light control module to see if that helps?

Sorry for all the questions. I'm only brainstorming here because I'm pretty much at the limit of my knowledge.

If anyone has any experience / knowledge / ideas which could help me out, I'd be very grateful to hear it.

Thanks in advance.

Tom