124 door locks open on their own
 

It's been awhile since I have been there.....I guess that is good and bad... I have been bus with other car projects..

anyway... on the 95 e 320... you can lock the doors internally or externally with a key...and a couple of minutes later they pop up automatically.

there is no aftermarket system on the car....

I've seen this problem discussed here before but don't remember what the outcome was. Search this forum and the diesel forum, it was in one of the two (or maybe both).

The later 124s have a couple of "convenience" relays that might be involved but I think I'd start by disconnecting the wires from the front door and the trunk lock switches one at a time, at the pump under the back seat. If you make up a couple of jumper wires, you can remove connector X2 (3 wires: blue, green, yellow) and connect any two, then test.

If you can narrow it down to one switch, you may find that that switch has gone bad and is not staying in the "lock" position. If it doesn't matter which one is disconnected, the problem should then be inside the pump, which probably means replacing the pump (expensive at dealer, inexpensive at junkyard).

Jeremy