Headlights always on!

[Steveamg]

W221 Headlights always on!

I had to remove the fuse box cover under the hood to check a fuse for the command display.

I have refitted as it was but I have noticed that when I start my car the headlight come and stay on! Changing the switch settings in the car makes no difference.

The day time running light settings work for the lower lights as it should via the menu on dash.

Can some one point me to where the sensor is for the lights? I believe it must be around the fuse area and I may have knocked it while removing the fuse cover?

Argggh

 

[whitenemesis]

The light sensor will be in the windscreen in front of the rear view mirror.

You have accidentally set the headlights to Constant On?

 

[Steveamg]

No, if I toggle the interior light switch to 0 A or on it has no effect .... Lights stay on as soon as I start the car.

This has only happened since I opened the fuse box under the bonnet (drivers side)

I see light/rain sensor fuse is 126 ... Will take a look at this.

Such a pain!

 

[whitenemesis]

There may an option in the Convenience menu in the cluster that sets the headlamp to Constant On, nothing to do with the main rotary switch

 

[Steveamg]

There may an option in the Convenience menu in the cluster that sets the headlamp to Constant On, nothing to do with the main rotary switch

That option is for the day time running lights located in the front bumper - the option to toggle on and off works fine for those lights.

Issue is still present with the main lights though.

 

[Birdie123]

Hi Steveamg,
I know yours is an old post but I am now having same issue with my car, did you ever manage to sort yours out, if so what was your solution please

 

[bob6600]

Hi Steveamg,
I know yours is an old post but I am now having same issue with my car, did you ever manage to sort yours out, if so what was your solution please

What did you do prior to this happening? It could have lost the country settings but more likely to be the light sensor as said

 

[Birdie123]

I had a battery drain issue, I took it to a garage who played around and messed up the lights so they started coming on all the time the ignition was on, prior to this no such issue, the garage then told me it was the headlight control unit that was faulty, presume they meant ballast unit, not sure I have a ballast unit as my lights are standard not Xenon, just ordinary halogen H7 bulbs
I then took the car to a proper auto electrician who traced the battery drain to the radio and phone cradle and that is now resolved but I am left with the headlights always on issue.

 

[Birdie123]

Still have this problem, turn on ignition key, sidelights and headlights come on regardless of rotary switch position, replaced rotary switch, no change, so not the rotary switch, unable to turn on foglights as rotary switch operation makes no difference but when I lock car with fob, I can see the foglights come on so they clearly work? main high beam comes on by pushing the light LEVER switch up or down. Have booked it in with mercedes specialist for STAR diagnosis, told it will need 2 hours cost of £156, probably more to fix....can't find an alternative cheaper good electrician locally

 

[Birdie123]

sorted, after all the fuss, turned about to be bad fuse no28