Philip LeBlanc

Hello, After searching the forum and not finding an answer, it is time to post a question: On a 2003 ML500, does anyone know where the headlight sensor is located? Does anyone have knowledge of auto headlight issues with an M Class? (Ok, that was two questions). I always leave the lights on "Auto" mode. A few nights ago, I started the car and the lights came on for a second or two and then shut off. Turning them on manually, they work fine. Auto has ceased to work. The world isn't going to end because I have to manually activates the headlights, but I didn't realize how convenient auto headlights actually are. I will ask the dealer to check into this matter when the car goes on for it's next service, but if it is a simple fix, I would like to do so myself. Thanks in advance for your help.

twenty2

i can answer one of your questions. The sensor for the auto lights is on your dashboard. A little round plastic bubble piece sticking up. You can't miss it.

Philip LeBlanc

Thanks... I thought that might be the sensor. I actually pried it up and looked at as if looking at it wold do something (kinda like those folks who stand there and look intently at the engine of a car that won't start). I might try to replace it and see if doing so will fix it.

Philip LeBlanc

Hi, me again, it took a while to get the part in. My local dealer ordered it for me ($40). I had high hopes of that simple swap restoring the auto operation of my headlamps. Didn't work. The lights work fine in all modes except auto. I checked to see if there was a specific fuse ties to auto operation but did not find one. I guess I'll live with it until it is time for the next service at the dealer and have them check it out. The only other issue I am having at present is the driver's seat heat works only on the back portion and not the bottom portion. I suspect that is an expensive fix. Any other thoughts on the headlamp issue? Thanks in advance.

neilpilot

Do you happen to have your original battery? Sometimes various systems such as autolights will fail randomly and, even though the car starts fine, the older battery has diminished reserve and needs to be changed.

Philip LeBlanc

Actually the battery was replaced several months ago. Of all days for it fail, it was a day my wife was driving the car. I called MB Roadside assistance and a tech came out and installed a new battery at my wife's office. The price wasn't bad either. If the new battery were defective, it would show signs such as sluggish starting, right?

neilpilot

Not in my case. Absolutely no starting issues, and no low voltage warning.

See my other posting on this: https://mbworld.org/forums/showthrea...108&highlight=

Mike's ML

My auto headlight sensor is in the rain sensor at the top of the windshield.
When I cover the rain sensor during the day the headlights come on. When I uncover the rain sensor during the day the headlights go off. Covering whatever that is on the top of the dashboard does nothing.
Mike

Philip LeBlanc

I figured that out the hard way. There is an expert who is always on the forums who I sent an email about this issue. He has a shop in Houston, TX. I'll be in Houston in a few weeks. He offered to check it out for me. I'll let you know how it goes. For what it's worth, my rain sensing wipers work fine. The only issue is the auto headlights.