Door lock/unlock diagnosis
Thread Starter
Newbie
Joined: Jul 2011
Posts: 13
Likes: 1
2009 GL320, 2010 E350
Door lock/unlock diagnosis
2010 e350.
Left rear door will neither lock nor unlock via fob or central locking (not keyless go).
Manual operation of the lock works fine.
No noises.
All 4 fuses good.
No error codes in xentry at all.
Actuation signals in xentry read out, but nothing happens.
It used to be intermittent, now it's been permanent for a year or more. My drivers door lock started to do the same thing a couple months ago and DID give an error code 98b101 The output for the central locking motor has a malfunction. There is a general electrical fault. I replaced the driver door actuator but the old unit started functioning while I was taking the panel apart, leading me to believe there's something electrical like a frayed wire in the door jamb causing the rear door failure, but wouldn't that drop a code?
Is there anything else to check before I rip apart the rear door and replace another $150 part?
Left rear door will neither lock nor unlock via fob or central locking (not keyless go).
Manual operation of the lock works fine.
No noises.
All 4 fuses good.
No error codes in xentry at all.
Actuation signals in xentry read out, but nothing happens.
It used to be intermittent, now it's been permanent for a year or more. My drivers door lock started to do the same thing a couple months ago and DID give an error code 98b101 The output for the central locking motor has a malfunction. There is a general electrical fault. I replaced the driver door actuator but the old unit started functioning while I was taking the panel apart, leading me to believe there's something electrical like a frayed wire in the door jamb causing the rear door failure, but wouldn't that drop a code?
Is there anything else to check before I rip apart the rear door and replace another $150 part?
Out Of Control!!
Joined: Apr 2019
Posts: 11,555
Likes: 6,589
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
bad lock!
2010 e350.
Left rear door will neither lock nor unlock via fob or central locking (not keyless go).
Manual operation of the lock works fine.
No noises.
All 4 fuses good.
No error codes in xentry at all.
Actuation signals in xentry read out, but nothing happens.
It used to be intermittent, now it's been permanent for a year or more. My drivers door lock started to do the same thing a couple months ago and DID give an error code 98b101 The output for the central locking motor has a malfunction. There is a general electrical fault. I replaced the driver door actuator but the old unit started functioning while I was taking the panel apart, leading me to believe there's something electrical like a frayed wire in the door jamb causing the rear door failure, but wouldn't that drop a code?
Is there anything else to check before I rip apart the rear door and replace another $150 part?
Left rear door will neither lock nor unlock via fob or central locking (not keyless go).
Manual operation of the lock works fine.
No noises.
All 4 fuses good.
No error codes in xentry at all.
Actuation signals in xentry read out, but nothing happens.
It used to be intermittent, now it's been permanent for a year or more. My drivers door lock started to do the same thing a couple months ago and DID give an error code 98b101 The output for the central locking motor has a malfunction. There is a general electrical fault. I replaced the driver door actuator but the old unit started functioning while I was taking the panel apart, leading me to believe there's something electrical like a frayed wire in the door jamb causing the rear door failure, but wouldn't that drop a code?
Is there anything else to check before I rip apart the rear door and replace another $150 part?
My wife held on the door handle a while ago while I was unlocking the car... now I have a hard fault that means a defective lock motor.
My 4x DCU modules are resoldered so it's guaranteed to be the poor connection of the tiny 12v motor inside the lock.
Something like this $15 gem...
female connector slots...
The bad news is MB uses metallic RIVETS to secure door inner panel... easy to drill out but not easy to match replacement.
I have no autopsy'ed lock module... it may feature a solderless interface to disfunction gradually.
Last edited by CaliBenzDriver; Apr 3, 2024 at 06:22 PM.
Thread Starter
Newbie
Joined: Jul 2011
Posts: 13
Likes: 1
2009 GL320, 2010 E350
I replaced the actuator, but that wasn't the problem. I could hear a constant buzzing after replacing it, like it was trying to lock or had low voltage. I tested the door control unit and it was getting 12v when switched. Sorta stumped I bought a $20 replacement control unit on ebay and that fixed it. Weird that it didn't give any error code, but whatever, it works now.
