I have a problem with my central locking system that seems very strange. Starting with the outside locks (using the key)...unlocking and locking from the driver's door works fine. Unlocking and locking from the passenger door or the trunk will activate all locks except for the driver's lock. Only on rare occasion, once or twice a month, will the driver or passenger lock activate the driver's lock as well.

From inside the car, the driver's door does not unlock any of the other doors, unless the car is on. With the car on, the entire system works fine. So, when I turn off the car and open the drivers door from the inside, only the driver's door unlocks.

From doing a search, it sounds as if something is wrong with the driver's side vacuum. I know on the 123s that there is a diaphram in each door...not sure about the 124. What would I need to replace in order to get the system working properly?

Thanks in advance.
Matt

You need to start troubleshooting your door lock vacuum system. Using the Mighty Vac test each and every component associated with this system. Something is not holding vacuum and you are probably correct that it is the vacuum actuator in the drivers door.

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Jim

Same thing happened to my '94 wagon. The cause was a slowly dying main vacuum pump which is under the passenger rear seat. The cost was about $230 for the job. If your pump makes noise for 3 + seconds after any doors are locked or unlocked then I would bet it is the main pump.

There's one more thing that I forgot to mention... The driver's door makes a loud noise (loud vibration?) sometimes after I unlock it. It lasts for 5-10 seconds. It doesn't seem normal.

Could it be that I need a new pump?? I hope not. If I took off the driver's door panel, what might I look for inside... where is the actuator located in the door? I don't have a mighty Vac, unfortunately, so I was thinking that I could just replace the driver's actuator and see if that fixed the problem. Not a good idea???

Thanks again,
Matt

94 E320

They have a tool loan program and it is FREE, just have to leave a deposit. They have the Mighty Vac! I KNOW, I used it before.
Good luck!

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J.H.
'86 300E

I finally got a chance today to take off the door panel and look for the problem. The door actuator looks fine from the outside (no visible damage to the rubber. But, it does make a loud vibrating noise (humming) after you unlock the door and makes a leaky noise from inside after you lock it. Could there be a leak inside?? Thanks.
Matt

The door panel has been off for several days, and haven't had time to look at the vacuum closely. The vac. element makes a loud hissing when locking and loud vibration when unlocking, until the pump stops working. It sounds like the pump is trying to keep pumping because it senses a lack in pressure. Is this normal? The noise lasts for 10-15 seconds. I'm currently debating whether to just go to the dealership and throw down $45 on a new element, but don't want to fix something that isn't broken. Thanks for all the suggestions so far.

Matt
1994 E320 (124)