1993 240-Removed driver's side door handle today because I had to adjust the little barrel shaped thing which sits in the back side of the handle that screws onto the rod which opens the door. The handle was almost not opening the door, had to pick it way up with both hands. When I was in there noticed the 3 wires coming out of the bottom of the electric lock were missing insulation, so I patched them up
When I reassembled everything, door now opens fine. However, the driver side door lock will NOT go down either manually or with the key. If I manually rotate the driver door latch 2 clicks(simulating the door being closed and latched), then the lock works. Also if I disconnect the little rod coming out of the bottom of the lock plunger assembly, then the lock can be depressed.
Hard to see the assembly in the door to find out what's wrong.
Any ideas?

 

The lock is designed not to go down as long as the door is open. This is supposed to keep you from locking your keys in the car. You state

If the lock doesn't work when the door is closed then it seems you may need to adjust the striker to ensure the latch is fully closed the two clicks when the door is closed..

 

I often will trick mine . first I make absolutely sure I have my keys, then open the back door and lock the button on the front door, thus locking them all up without putting my key in the door.

the fact that I am needing to do this, confirms the post above.