Mh159

I’m having an issue with the passenger side front door lock. If it is locked, it won’t unlock when I hit the remote. If it is unlocked, it won’t lock via remote. All the other locks respond. I can push it down with my hand, and pull the handle inside to unlock, but it doesn’t respond to the remote. Does anybody know what the fix is for this? It would be good to also know the cause as the same thing happed to my W203 (same door). I'm taking the panels off tomorrow to install new speakers and it would be great if I could get this fixed. Thanks for your help!

JettaRed

iTrader: (1)

Do you have a scanner like an iCarsoft MB V3.0 or a LAUNCH Creader Elite BENZ? If not, get one and find out what is really wrong with your car before dismantling it.

HBguy

If you're taking the panels off, you can see if you're getting volts to the motor when you hit the switch. It sounds simple enough, bad motor. Unless someones taken that panel off before and loosened a wire. You can also apply 12v directly once the panels off.

TimC300

I never messed with my door locks so im just going off pictures im finding. Appears the door lock assembly is easy enough to separate once its removed, a few plastic tabs to get it apart. Then id get the multimeter out and start testing the connectors going to it, then to the small electric motor to confirm its getting voltage when the remote being pressed. Could be a burned out motor. Can always try spraying a little silicone lube in the door lock area, maybe its stuck just enough where the electric motor has a hard time operating it but can still operate it by hand. Does the door lock feel the same on all doors, meaning does the problematic door feel harder to lock/unlock by hand?

HBguy

Try to do as much as you can without taking things apart. The hard part is putting it all together with plastic parts.

StraightWisdom

I have the same issue with the front passenger door lock on my 2010 C300 sedan
I bought the car used and I've chopped it up to it being a bad motor, but I haven't done anything to asses or confirm that.

So we have to manually lock and unlock that door. If it's like a $200 fix, I would just pay for it, but from what I'm looked into into the past it could be double that.. so I'm just holding on till it's really necessary. It's the same reason I wont change the door pin. for shorter ones for the look, because it will be so low that you can't manually pull it up

TimC300

If I had an issue with a door lock I would probably look for a used replacement on eBay. $40-$80 used. They have new unbranded units for around $45, but I personally wouldn't chance it with having bad experience with non-Mercedes parts already. I would take everything apart first to confirm the exact issue.