Do the headlights run a self test if they come on when the light switch is in the auto position and the lights come on because the ambient light level drops? I ask because on my journey to work I pass under trees and the lights go on then off, then on again. I would have thought that a self test when the car is moving would be dangerous and probably illegal! :wonder:

Alan

Edited 14 September, 201114 yr by alannfrost

I always leave my lights on "Auto" although mine of Xenon's rather than Halogens.

I'll admit that my auto-lights have so far (6 months of ownership) been very good and only come on when it has indeed got dark.

Travelling under tree's hasn't triggered them, except when we were under a very extended cover.

When my Xenon's switch on they do indeed self-test and if that is while I'm driving along then so be it.

I'm not sure why that would be illegal.

The lights drop before doing their side-to-side test, so no chance of dazzling anybody whilst the test is being run.

I always leave my lights on "Auto" although mine of Xenon's rather than Halogens.

I'll admit that my auto-lights have so far (6 months of ownership) been very good and only come on when it has indeed got dark.

Travelling under tree's hasn't triggered them, except when we were under a very extended cover.

When my Xenon's switch on they do indeed self-test and if that is while I'm driving along then so be it.

I'm not sure why that would be illegal.

The lights drop before doing their side-to-side test, so no chance of dazzling anybody whilst the test is being run.

Yes I wondered what they were doing when I first noticed it, although I note it doesn't seem to do it every time.

Ooops - meant Xenons

When my Xenon's switch on they do indeed self-test and if that is while I'm driving along then so be it.

I'm not sure why that would be illegal.

The lights drop before doing their side-to-side test, so no chance of dazzling anybody whilst the test is being run.

No they don't - they only self test when the engine is first switched on whether the lights are on or off and definitely not whilst moving as you can interupt the test by driving off forwards or backwards.

Mine come on and off under tress all the time - it just detects the difference in light for tunnels so if it is a sunny day and you got through a tree covered lane it will think you are in a tunnel.

I have light sensor but with Halogen headlights, it seems to change it's mind daily as to what it considers to be dark enough, sometimes a few trees brings it on, sometimes it doesnt, I just think it's a quirk of the system!