S Class Auto Headlamp Confusion

[tlzeebub]

My auto headlamps seem to be confused, driving to work this morning in the brilliant sunshine and my car thinks i need the headlights on, when i go home tonight it'll be just as bright and they wont come on, is it taking into account the time? or does it need re-calibrating somehow?

 

[Diesel Benz]

Assuming you want them on all the time, just activate DLR from the cluster menu.

I guess you are from the UK and actually want them off when there is enough light. This has been discussed and the conclusion should be that the light sensor does not see the sun light equally when it comes from very low. Actually should be very good, if you don't see lights helping to avoid accidents at daytime, those would help specifically when the sun may blind others. Like it or not, nothing much you can do about it.

 

[tlzeebub]

Thanks DB yes i am in the UK and i dont want them on all the time, when i left work this evening they weren't on after a bout 5 miles i went through a short tunnel and they came on after i exited the tunnel they still remained on until i got home some 20 miles later and they only went off when i turned off the ignition, i didnt see any other cars driving with there headlights on, so i think something is wrong.

 

[Chas]

What time of day are you driving ? The ambient light is picked up by the sensor, and even if the sun is above the horizon they may still come on.

Early morning light is not very bright. It does seem you have a problem with them though, perhaps the automatic lighting control module is faulty ?

 

[tlzeebub]

Thanks Chas morning journey between 0630-0700, evening 1700-1745 and it was very bright at both times yesterday, do i need a STAR diagnosis to check the lighting control module? by the way i like the front grille on your picture what's it from?

 

[Diesel Benz]

I understood that the car anyway does switch lights on and off. Shouldn't it be more likely the light sensor instead of the control unit then? You can test the sensor at a carage, inside with a torch. Difficult to "calibrate" but you would get some idea anyway how it works.

 

[Chas]

Its not uncommon for the front SAM module to be faulty in two to three year old cars

Does your Comand screen change colour when the the lights go on and off?

 

[tlzeebub]

Its not uncommon for the front SAM module to be faulty in two to three year old cars

Does your Comand screen change colour when the the lights go on and off?

Thanks Chas my comand screen does change at night but it seems to work independent of the lights, the comand seems to change at the right times but my headlamps will quite often stay on even when the comand screen returns to daylight scheme, hope that makes sense.

 

[Chas]

It might just be the light switch is giving spurious faults on the auto setting. Try removing it and replacing it

 

[whitenemesis]

Could it be the low angle of light that is confusing the car? I believe the light sensor is made up of two sensors. The first is quite exposed and determines the general light level. The second is partially buried in a short tunnel. This second sensor seees only low angle light and prevents the lights going off because of an oncomming vehicle's headlights artificially raising the light level seen by the exposed sensor.

On many occasions my lights will come on in the morning or evening at a time I would have though too soon because light levels are quite high but the sun is quite low.

 

[Chas]

the comand seems to change at the right times but my headlamps will quite often stay on even when the comand screen returns to daylight scheme, hope that makes sense.

Strange though, if the COMAND screen is changing colour as it should and the headlights are out of synch.

 

[whitenemesis]

Strange though, if the COMAND screen is changing colour as it should and the headlights are out of synch.

I thought COMAND had it's own ambient light sensor?

The illumionation in the Thermotronic seems linked to the headlights though....