2006 ML350 headlight won't turn off
 

Last night I noticed that one of my wife's headlight (the parking light actually) was on. Just the right front one.

It will not turn off. She turned the car on and took the headlight switch off "auto" and turned it to "off" and the light still won't turn off.

I went into the fuse box(es) to try and at least remove the fuse to force the light off, but for the life of me, I can't find the fuse that controls those lights. In the fuse map, there is nothing that says "headlights" or "parking lights".

I removed the fuses for "headlamp range adjustments", "switch panel" and "light control switch" and even after having them out for 5 minutes, the light still did not turn off.

Anyone have any experience with this? Know what it is? How to turn it off / fix it? I really would like to avoid spending hundreds of dollars for what appears to be a small fuse/wiring issue.

Electrical Problems
 

This is the same thing that happened to my 92 300d. There would probably be a problem with your battery. Try disconnecting it and connecting it again. If this does not work, the battery might have to be replaced.

Thanks, I tried to do that earlier today, but for some insane reason, the designers of the ML 350 thought it wise to put the battery, not in the engine where it would be easily removeable, but behind/under the passenger seat.

So it's a nightmare to even get to, and then when you do, you can really only get to one side of the battery. I realized after I posted this last night that maybe just unhooking the battery may be a fix, but it seems impossible for me to do that without getting under the car or taking the entire seat out.

Did you take notice if any of the rear lights are on? Mercedes cars have the side street parking lights where you can leave on the left or right side park lights. there is a switch position for these.

if none of these are the case then I would say you have a wrong bulb installed or you've got other issues with water getting into the car, or other electrical issue.

Did you figure this one out? I just replaced the ballast for my headlight and now it stays on whether the car is on or not. I checked a couple fuses, but all were good. I also tried disconnecting the battery for awhile.

Unfortunately, not. Our long-term fix was just disconnecting the wire to the light so it didn't drain the battery.

We took it to a Mercedes Dealership and even they couldn't figure out what was wrong (though honestly, we were there for another reason and I asked if they could take a "quick look" and they probably just ignored it.)

From my quick research, it looked like it needed a new headlight switch and it's not a completely uncommon problem. But I didn't feel like spending the time and money to replace the switch since I'm not especially savvy around cars and assumed I would ruin it and make it worse.

Thanks for the update. Sounds a lot like my planned "fix".

Sorry I realize this isn't exactly the same issue, but I couldn't find anyway to insert a new thread, and it does pertain to the ML 500 and I want to see if anyone on here is having the same experience as me. We bought a 2006 ML 500 a few years back and have had problem after problem But this one takes the cake....
This truck seems to be "haunted" or something. We started having issues with it as soon as the rainy season started and it hasn't let up. I will get random red warning lights that show up on the dash, SRS, Brakes, Visit Workshop, Battery, you name it and when that happens, things will either stop working, or will not turn off, like the engine, the lights, the wipers, the windows, on and on. We finally acquiesced and bought new batteries and replaced them last week. {both the large one and the small aux. battery. It worked great for about 4 days, then it started in again. At the worst possible time, during a rain squall driving in the city, I lost my windshield wipers, the windows would not rollup, the engine would not turn off! { for a point of reference, its been raining since labor day and it does not do it every time we drive in the rain. } We were able to pull over and finally was able to turn off the motor. {granted this was after 5 min of the key being out of the ignition} but then after reinserting the key, turning it on everything worked fine! WTH???? On top of this we took the old battery into the parts place in town and they tested the battery. It was GOOD. So it obviously is not the battery. Has anyone been experiencing this? We know all about the water in the floor of the passenger side, and there has not been any as far as we know. but living in Seattle it is evident at some point water will get on the car. If anyone can give me an idea of what to look at that does not involve taking it to a DEALER. They charge you $200 just to pull into the lot.
Thanks all

Me toooo!
 

Hi there!
Im experiencing The exact same problem on a 2007 ML 320. And it has to do with the rain, that's for sure. It started with a tropical storm here in Hawaii and the weather has not changed for weeks, it's raining, I mean pouring down, every day. The problems got worse and worse, just like you described. I exchanged the battery, and the alternator, put in $1500 by now and nothing has changed. Have you found a solution yet?