1998 ML320 remote lock problem
 

Recently all the remote or electronic locking/unlocking for the 4 doors on my 1998 ML 320 quit working. Neither the switches on the console nor the electronic buttons on the keys will lock or unlock the doors. However, the trunk lid works. Any ideas. We recently had the bumpers off. Could a wire have disconnected?

Have you checked the fuses under hood OR tried swapping the locking relays in the fuse box?

fuses and relays
 

Fuses are ok, but I have not checked the relays. However, I am confused. Are there separate relays for each door and the back lid. Seems strange that the relay for the back lid would still be working, but the 4 doors would all go out simultaneously. Are the doors on one relay and the back lid on another? If so, it would make sense. Can you tell me how to find the relay for the doors or is there a drawing you can post?
Thanks for your reply and help.

fuses and relays are ok. Locks still don't work.
 

I checked the fuse and interchanged the working relays for which the parts numbers match. Door locks still do not work. The liftgate opens and closes just fine. However, the 4 doors and the gas flap neither open nor close. I can feel the correct relays open and close when I push the corresponding button on the key.

Still looking for ideas. Since none of the 4 doors work, it can't be individual actuators (unless they all 4 burned out simultaneously). Are the connections to the doors electrical or vacuum? Where is a central point to start the search for the fault?