SAguirre

Hello all,

I just noticed this last December that my trunk lights (all 3 of them) sometimes have a bit of trouble staying on when the trunk is first opened. I first noticed this when I was in the mountains in Northern CA. It was freezing and I got some snow in the trunk (but not much) when I opened it. There is a lot more humidity in CA than in CO, so I thought some moisture must have gotten in somewhere. When I first open the trunk and up to when the lid opens to 1 foot, the lights would stay on. Once the lid got past the one foot mark, then lights would turn off.

Once I got back to Colorado everything was fine once again. But I just noticed it did it again the other day, the car has not been exposed to ANY moisture in over 4 weeks. So the car is bone dry.

Has this happened to anyone? Does someone have the schematics of the trunk lighting system, more specifically, where is the switch and and kind of switch is it? I have a regular old trunk, no automatic closer.

My Soprano button still works fine and there are no other issues in the back of the car that I can link to this. So I think I might have a bad switch. I do tend to park the car with the trunk open for months at a time when the car is not driven, the lights DO turn themselves off after a few minutes and then they work fine after I close and reopen the trunk. I have a battery maintainer that I plug in the trunk. Leaving the lid open lets me get the power cord in by the maintainer and also reminds me to unplug it before I back it up out of the garage. Perhaps the switch does not like being in that position for that long. But, My car is now 9 years old (from date of production) and I still have the original two batteries that are still at full power! Even when I was in the freezing weather all December, the engine cranked very quickly, so I swear by the maintainers!

Any info would be greatly appreciated!

Steve

Craftysince86

sounds like a short

SAguirre

I checked and it is not a short. There is no strange draw on the circuit when this happens. Also, if it were a real short, the fuse will burn. So far, I have never changed a fuse in this car.

I think that it is the switch, but I don't want to hunt for its location, if someone knows where it is.

Thanks,

Steve

konigstiger

Check the wiring harness - driver side, trunk hinge https://mbworld.org/forums/e-class-w...ate-lamps.html (see post 14 & 15).

SAguirre

Thanks for the suggestion!

Everything works well. The third (trunk mounted) brake light works even when the internal trunk lights act up. I had to have someone press the brake pedal while the ignition was on, then I open the trunk and the lights flicker, then turn off. The green Soprano button still works and blinks (as it should) the brake light on the trunk lid also works.

The last time I checked, the internal trunk lights were working as they should and I could NOT get them to act up. I believe that the switch is bad, but I would love to know where it is. Otherwise I will have to go to a hunt for it and waste time. I would like to bypass the switch when the lights are acting up, then see if they still act up after the bypass.

Any schematics would be great!

Steve

DanG2

It appears from the STAR Service CD that the S88/6 Trunk lid contact switch is part of the trunk latch mechanism in the trunk lid. You'd need to remove the trunk lid inner liner to get to it. It says it's a normally closed switch that grounds an input to the rear SAM, and the SAM then outputs power to the lights.

If I'm reading the wiring diagram correctly, the switch has a brown wire that goes to ground, and a green wire that goes to Terminal 4 on the SAM. So if the trunk is open and the lights are not on, you should be able to jumper Terminal 4 to ground and see if the lights work. If they do, the problem is in the switch, or in the wiring from the switch per Konigstiger's post. If they don't work, the problem is in the SAM, or I'm not reading the wiring diagram correctly (which is entirely possible).

SAguirre

Thank you VERY MUCH! I have just been toying with the lid over the weekend and I am now of the opinion that my wires/cables on the driver's side hinge must be about to break. However, it might be the switch. I will see when I will get around to testing the circuits.

I will post here what I find. For a second, I thought that the switch might be an angle detecting switch (like the old mercury switches). If it is in the lock mechanism (which makes sense) the bus is getting fooled when the cable in the hinge is being cut off for a second and the signal that the latch was opened is interrupted.

One of these weeks I will go on the witch hunt.

Thanks!

Steve

lphillips1117

I'm having the same problem on my CL55. Everything works except the interior trunk lights and the power close feature. The power open is perfectly fine though. I found what I believe to be the trunk open/close sensor. When I tested it with a multimeter, there was a distinct connection between connection 2 and 3 when closed and 1 and 2 when open (or vise/versa) but the wires leading to it only show ground on 1. I haven't been able to locate a short yet but I'll keep looking. The problem started with the interior lights flickering as I opened the trunk one night. Once I got past the half way point, they went out and that's then the power closed stopped. Not sure about the W211, but on my W215, the open/close sensor is on the passenger side above the battery, behind a 1" diameter silver horizontal tube. There are 2 torx screws holding it in place.