On my '88 240DL, the power locks have developed a problem:
- driver's key unlocks 3 door's but not driver's door
- driver's key will not lock any doors
- driver's door interior lock plunger will lock & unlock all doors reliably
- problem just started with recent rain

Any ideas? Thanks...Lyle

I have some ideas--but don't know if they make any sense given that you seem to have both a mechanical and electrical problem---unless--maybe the rotating bar attached to the back end of the lock cyl (one small machine screw) has come undone. That bar fits into a cage operating the lock part of the latch--the cage is in combo with a flat link that has the door lock stem attached. When you turn the key to lock or unlock the driver's door the cage/flat link is driven to pivot into the lock or unlock position on the latch. The stem is also attached to that flat pivoting link. A switch for the 3 other doors actuators wraps around the cylinder and is activated when the key is turned. A second electrical switch is built into the stem link--a spring loaded plunger kind of deal. That link/switch must be ok if it locks/unlocks the driver's door (mechanically) and the other doors (electrically through the actuators). If the key will not lock/unlock the driver's door the mechanical connection (rotating bar) must/might not be doing its job. Maybe it is attached enough to operate the cylinder switch in one direction--but not the other. In any case the interior panel will have to come off to make a complete diagnosis/repair. Clear? - lol -- Dave

The lock cylinder had 2 problems: the casting at the end broke, and the spring underneath it broke. I got another lock from a junker, and fortunately both parts were replaceable by removing a cir-clip. The electrical harness surrounding the lock cylinder was also questionable, so I replaced that with the best used one I could find.

Thanks to all for their advice...Lyle