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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4946
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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2009 GL320. Left rear door lock will lock but will not

Customer Question

2009 GL320. Left rear door lock will lock but will not unlock. I installed a new actuator mechanism, guess that wasn't the answer. I am trying to operate power locks from the driver's door. How do I repair this? Thanks jack
Submitted: 1 year ago.
Category: Mercedes
Expert:  Lou P. master tech replied 1 year ago.

Hello, what kind of diagnostics did you do to confirm the lock was bad? it sounds to me like the door module will not activate the lock in the unlock position electrically. ill check a diagram see what we can find. also does the door work when using the remote to lock and unlock?

Expert:  Lou P. master tech replied 1 year ago.

actually the rear sam actuates the locks on this model in the rear.

Expert:  Lou P. master tech replied 1 year ago.

so since the same wires are used for lock and unlock we know the wiring is good. it has to be the rear sam that is the issue. the rear sam is located in the right rear under the fuse box roughly. connector F pins 21 and 22 are for the lock motor, colors are 21 white and 22 violet with a black stripe if you want to do a continuity check, i suppose the only other option would be if one of the wires were shorted to ground that way it would only work in one direction when power was activated on the correct wire. hope this helps, i would ohm both wires to ground while both sides were disconnected, both from the lock and the sam. hope this helps. Please take a second and click the stars at the top of the screen to rate me so i may receive my credit , 5 stars is ideal , please request me in the future.
Keep in mind then when you rate it does not end our conversation. you can still return here to me for follow up information if needed, Lou P.

Customer: replied 1 year ago.
we replaced the rear lock because that has fixed the problem on every chevy and dodge. Now that I am using the remote I notice that the driver's door lock does not function either lock or unlock and same when using inside button. Left rear door acts the same with remote and button.
Expert:  Lou P. master tech replied 1 year ago.
Ok if you are trying the locks with the drivers door open it will not lock or unlock
Customer: replied 1 year ago.
when are those buttons mounted on all of the exterior door handles supposed to work? they don't do a thing. This "SAm" some kind of module? Is there more than 1 module for the locks like front and rear?
Expert:  Lou P. master tech replied 1 year ago.
Ok so if you have the small black button on the door handles that means you have the keyless go starting system. Make sure it's a button. Not a small plastic window for the express open and closing. If the vehicle has the push button start in the ignition then it has keyless go.
Expert:  Lou P. master tech replied 1 year ago.

The buttons lock the car when the doors are all closed. And the door will automatically unlock when your hand is placed inside the door handles

Expert:  Lou P. master tech replied 1 year ago.

And no , as I have explained the wiring goes from the lock to the rear Sam. The only connector is the door jamb connector and there are no other modules involved with the locks.

Customer: replied 1 year ago.
I have that plastic key that you put in and turn. No push button start. There are push buttons on all 4 exterior door handles. So do I need a new "SAM" a lock module I guess? Will it need dealer programming?
Expert:  Lou P. master tech replied 1 year ago.

if you have the push buttons on the handles then the customer may have lost the plastic push button that just snaps into the ignition switch, as for the sam, yes you need to have it programmed, BUT i urge you to perform the wire test to make sure , from what you describe it is very very possible that one of the wires is ground out somewhere. Please take a second and click the stars at the top of the screen to rate me so i may receive my credit , 5 stars is ideal , please request me in the future.
Keep in mind then when you rate it does not end our conversation. you can still return here to me for follow up information if needed, Lou P.