1982 Mercedes Benz 300sd Vacuum door locks

CRBOBR

MEMBER
1982 MERCEDES BENZ 300SD

Interior problem
1982 Mercedes Benz 300sd Two Wheel Drive Automatic 134000 miles

When I bought my car, the vacuum door lock system was disconnected. When I reconnected it, I found out why. When the driver door is locked, all of the other doors lock. Just as they are supposed to do. THEN. They unlock. Then they lock again. Then they unlock again. And this lock/unlock cycle continues until the driver door is unlocked. Then the cycle stops in the unlock position. So. I'm unable to lock the doors at all. Either from inside or from outside using the key. I can disconnect the vacuum at the pump in the trunk, and manually lock/unlock each door but they are very stiff to operate.

1 Reply

BUDDYCRAIGG

MECHANIC
2,262 POSTS

Sounds like one of the sensors that tell the car that the doors are locked is not working, OR since you said they are stiff, then the lock is not moving far enough to flip the switch.

So it keeps trying to get the lock to move all the way.

It could be inside any of the doors.

You might be able to manually help the lock at each door to diagnose which door is the problem, otherwise you'll have to take the inner panels off to visually inspect everything.