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2007 ML350 - As seen in the pictures the left tail lights are staying lit when swithch is in the off (center) position. All the brake lights work fine. I have checked the bulbs, the contacts are clean and there doesn't appear to be anything wrong with the cables or moisture. I wanted to check the fuse or fuses but the owners manual does not list them. I have found diagrams online but the diagrams do not actually say "left rear tail light" assigned to fuse XX. Note: The tail light bulbs are also getting extremely hot but nothing has melted, I caught it before anything like that could happen.
First,
could it be a fuse causing this and if so which fuse box and which fuse do I check? If not the fuse, what else? Thanks for reading.
Last edited by schmad1962; Aug 12, 2021 at 07:43 PM.
Reason: Forgot to add something.
There are no fuses or relays that control the lighting, so forget that..
You must access the rear SAM which is on the floor of the spare tire area and see if there is any water intrusion.
Even if there is no visible intrusion, with the key out of the ing. you must remove the SAM and remove the two plastic covers and see if there is corrosion.
So far I haven't seen any water damage to any of the boxes, but I did find this with 2 corroded loose/disconnected wires. What is this unit and how much does it cost or should I try to re-attach the wires, not sure yet how they attached in the first place. And, could this impact the lights in any way?
Last edited by schmad1962; Aug 14, 2021 at 11:26 AM.
Reason: Forgot to add something.
Ok so here is how it stands now, I capped off the hydraulic pump wires because we had those lift arms replaced with non-powered arms years ago so we do not use that anyway. When I turn the lights on whether the vehicle is started or not all the lights will light, for some reason the left bulb is brighter than the other (have already swapped and replaced bulbs). Sometimes the outer most left bulb will flicker before going out. Then,
when I turn the lights off whether the vehicle is started or not the right bulb goes off as it should and the left bulb stays lit for 20 seconds then goes out. If I open a door or I open the latch, the left light will light again and then when I close the door or the lift gate the bulb will then again stay lit for 20 seconds then go out. Is this some kind of warning light for something else or do I need to replace something? I have a video but the site won't let me upload it.
Maj Dundee,
You were right, there was corrosion yet again in the SAM board (see picture), I cleaned it again and that seemed to correct the "staying on and hot bulb problem" although the outer left tail lamp still does not light. I don't know how many more cleanings this board can take as the green part of the circuit board is starting to wear. So I sprayed liquid rubber onto that section and it did not seem to cause any harm and it should insulate and protect it. I am wondering if I should just spray the whole board with liquid rubber at this point to protect it in the future, could that cause issues? Otherwise, do you know of how I should protect the box from further moisture, I have already sealed the right tail light lens but obviously water is still getting in from somewhere else. Or maybe just position the box in a way that the water does not travel down the wires? Any ideas? Thank you very much.
I sprayed and cleaned it with contact cleaner, it is working at the moment, but I am looking out for a replacement, they are not cheap and some people say they need to be re-programmed and others say they did not need to, what is the real truth to that?
Maj Dundee,
You were right, there was corrosion yet again in the SAM board (see picture), I cleaned it again and that seemed to correct the "staying on and hot bulb problem" although the outer left tail lamp still does not light. I don't know how many more cleanings this board can take as the green part of the circuit board is starting to wear. So I sprayed liquid rubber onto that section and it did not seem to cause any harm and it should insulate and protect it. I am wondering if I should just spray the whole board with liquid rubber at this point to protect it in the future, could that cause issues? Otherwise, do you know of how I should protect the box from further moisture, I have already sealed the right tail light lens but obviously water is still getting in from somewhere else. Or maybe just position the box in a way that the water does not travel down the wires? Any ideas? Thank you very much.
I had a similar issue with my 2007 ML320 CDI.
On my vehicle, the right front turn indicator was always on. I removed the SAM from under the right front seat and found corrosion. I removed the board from the black container and cleaned it with 91% isopropyl alcohol to remove the corrosion. Then reassembled and reinstalled into the vehicle.
The issue has not returned in the 2+ years since I performed the repair.
I would at least try this before you source a replacement.
Is that SAM under the front right seat towards the back of the seat where the battery is or actually in front of the seat? Thanks.
Its under the seat. It's been so long since I did that. I recall removing the battery to get access to it. It probably would be easier to remove the front seat
Its under the seat. It's been so long since I did that. I recall removing the battery to get access to it. It probably would be easier to remove the front seat
I just recently replaced the auxiliary batteries and can confirm it is in a sh*t spot. Something so trivial made difficult just because it is in an awkward spot. I had the ML320 immobilised for 1 day because of this. If you can manage to squeeze in without taking out the front seat, then you are fine.
About the main topic. I am not an electrical guru but I have worked on some of them. Looks like a short circuit to me which your pictures of the rear SAM backs up the finding.
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Left tail lights staying lit
