automatic headlight sensor

[bmwrider]

Good morning everyone
Just wondering if anyone has had a problem with the auto headlights not
going off once you are in the daylight, they came on when I was driving
in the dark, now the only way they will go off is when I turn them off
manually, any body got any ideas on the matter

Cheers Kerry

[gregozedobe]

Check you haven't got anything on the windscreen obscuring the light sensor (up near the rear-view mirror mount). A Kamikaze bug may have splattered itself in the precise spot to stop light reaching the sensor, thus fooling it into believing it is always dark. Otherwise it may be a faulty sensor (not uncommon, but a PITA to fix AFIK). A search on "sensor" may yield additional useful info.

[buchs]

G'day mate,
I have had the same problem on my R32 from time to time. It seems to reset itself when the car is turned off but seems to happen again. I've checked and cleaned the sensor area on the windscreen but unfortunately the problem seems to be there intermitantly. It's booked in with VW on the 7th of April (earliest they could fit me in!) to have a faulty oxygen snsor replaced (common problem I'm told) and i'll have it looked at then.

Does yours stay on perminantly? or does it reset when the car is turned off?

-----------------------------------------
MY07 R32 3dr DSG Black, Sunroof, Sat Nav, TV

[bmwrider]

G'day mate,
I have had the same problem on my R32 from time to time. It seems to reset itself when the car is turned off but seems to happen again. I've checked and cleaned the sensor area on the windscreen but unfortunately the problem seems to be there intermitantly. It's booked in with VW on the 7th of April (earliest they could fit me in!) to have a faulty oxygen snsor replaced (common problem I'm told) and i'll have it looked at then.

Does yours stay on perminantly? or does it reset when the car is turned off?

-----------------------------------------
MY07 R32 3dr DSG Black, Sunroof, Sat Nav, TV

Hi
It stayed on for about an hour, and then I parked the car for awhile and it fixed it self, so far it been ok since

[xplainwhy]

Has anyone had to get this fixed by the dealer?

I have a similar issue where my car's headlights are on pretty much all the time, even in broad daylight. It's winter here in Sydney, so the sun isn't as strong as it could be, but even under clear blue skies in the middle of the day, my headlights will be on.

I've checked the sensor and there's nothing obstructing it.

[85turbo]

in my experience, the auto light sensor is a little too cautious / over sensitive.
i have had the lights come on, when a big cloud passes overhead (no joke) on an otherwise sunny day.....

Jason.

[warhead]

Mine was acting up again this morning. Was pretty bright and sunny in Melbourne and the lights decided to turn themselves on.

Does the auto headlights use any info from the external temp sensors? It was 5deg C outside this morning.

I've had other cases where the lights would come on for no apparent reason.

[G-rig]

Mine tend to stay on too long sometimes, but usually ok. Is a bit odd considering it may be a bright sunny day and switching from AUTO to OFF then back to AUTO doesn't alway turn them off.

[xplainwhy]

My experience with the headlights is very similar to 85turbo and warhead <edit>and G-rig</edit>.

Just wondering if it's worth taking it in to VW to get it looked at or not.

[Maverick]

The amount of light required to turn the lights on is different to the amount of light required to turn them off.

For example. It's a slightly dull day and you're driving along and the sensor is reading 1000 units* of light, you pass under a overpass and the amount of light units drops to under the turn on point of 900* units so the headlights turn on. You leave the overpass and the sensor registers 1000* units of light but doesn't turn them off because it requires 1100* units to light to switch off.

The reason for this is to prevent the constant on and off switching that you see some cars do (notably Toyota's and Honda's) when they go under overpasses etc.

I'm not sure how well it works but you can play with the calibration of the sensor using Vagcom/VCDS but if it's playing up the dealer will swap it out but it can be hard to demonstrate.

Mine works fine and once you understand how it works you may realise there isn't a problem there but normal operation. It costs pretty much nothing to run the headlights so just let them run if the cars want's to!

*I made up the units of measurement to make the example easier as it doesn't rely just on lumens.

[85turbo]

Obviously there has to be some degree of hysteresis (sp?) built in to the
sensor to prevent the on/off cycling that would otherwise occur, but I think the sensor is too sensitive at the turn on point.

The hysteresis is especially useful in cars with HID lighting, as HID does not cope well with rapid on/off cycling.
But as mine is not HID (for now) I'll check the calibration.

Might have to look at vcds for the settings.

Jason.

[JP2]

Good morning everyone
Just wondering if anyone has had a problem with the auto headlights not
going off once you are in the daylight, they came on when I was driving
in the dark, now the only way they will go off is when I turn them off
manually, any body got any ideas on the matter

Cheers Kerry

I feel embarrassing of the headlight sensor keeping the lights on under the sun, but never drive in dark.

Cheers james

[bazzle]

I feel embarrassing of the headlight sensor keeping the lights on under the sun, but never drive in dark.

Cheers james

If you do not want them on and never drive in the dark just turn off the light switch.

Bazzle