speed43

I hope one of you guys no the answer to this.

My trunk will not pop open when I press and hold the trunk button on the remote fob. It won't pop open even using the button in the middle counsel next to the mirror adjust buttons. The key itself will not open the trunk either. Everything in the car is working properly accept this issue. It started a week ago.

I don't see the littler light on the counsel like I believe it use to be a light there? I checked ALL the fuses and all of them are good.

I do not hear any noise like the air actuator either. Is there any way I can open this trunk?

Is there a light in the trunk release button and if yes what could cause the light to go out when all the fuses are good? Maybe more fuses in the trunk that might be bad? And if that's the case what was Mercedes thinking putting a fuse for the trunk in the trunk?...

Any suggestion is really appreciated. Thanks.

importfan21

I had a similar issue years ago (except my trunk release switch light was always on). Had to get my trunk cylinder replaced.

DRBC43AMG

If I recall the switch does have a small LED(?) light. If nothing works, I would suggest popping the switch out of the console and check for current, then bridge the wires. This way, if the switch is faulty, you could get to bypass the switch and perhaps open the trunk. If the trunk lock is faulty, then you may have to get to it from the inside of the trunk compartment.

speed43

Thanks. I hope that's not my issue but I will see.

speed43

I will try that before removing the back speaker so I can reach in and pop that lever to lower the seat.

I have another counsel I can swap so I will do that too. I'm just wondering if the switch is bad would that stop the key fob trunk button to not work too? Just wondering...

speed43

I did everything to get the trunk opened and nothing worked. Even trying to remove the rear speaker to get an arm and pull the rear seat lever.

I finally decided to cut the plastic inside the rear seat arm rest. I will either weld it back or replace it.

Anyway after cutting that plastic my daughter was able to get a flat lever and pry the mechanism and the seat popped. Then she reached in after the seats were down and she disconnect the battery terminal. That reset the ecu and I was able to pop open the truck.

Everything that pops the truck open now works. For how long I don't know.

Any reason why this happened that I had to reset the ecu for it to work again?

MattCordell

you have a possible leak or a bad vacuum pump in the trunk not operating switch or lock?
test with another pump or a car in better shape without issues.

DRBC43AMG

Glad to hear you found a solution to the problem and you could open the trunk.
However, you have me stumped regarding a simple disconnect of battery that solved the problem. Why it did this and will it do it again, time will tell. Is the battery old and loosing power over time perhaps?

speed43

Thanks guys.

pump has no leaks at all. And battery got replaced less than a month ago.

When you reset the ecu it usually fixes some electrical issues for a while. I had to do that on another c43 that the seat would stop working all of a sudden. Resetting would fix it for a few weeks each time. Than I found it was a relay and that fixed it for good.

So I'm thinking this is an electrical issue too and that's why the reset works, at least for a while.

Benzgurl75

Try holding the key fob up to the trunk and push the trunk release button on ur key fob at the same with the trunk button on ur car works like a charm.

speed43

Well it works now because I reset the ecu by disconnecting the battery for a minute. If it goes bad again I will try what you said but honestly I doubt that will pop it open. Once it stopped working nothing would open it. It was as if there was no electricity going to the accessories. But of course there was and everything worked accept the buttons that suppose to open the trunk.