Power locks
 

The power locks on my 85 380SE have quit working all of a sudden. I never had trouble before. Could it be a fuse, or does it a vacuum problem? Anything else I should look for? As I say, it has never given me a problem before and just stopped working - they all opened and then they wouldn't lock.

The locks are operated by a vacuum/pressure pump in the spare tire well. Have someone operate the locks while you listen for a whir from the pump and go from there.

Does it not work using the key? Does it not work using the driver's lock button? Does it not work using either?

Sixto
91 300SE
87 300SDL
81 300SD

Doesn't work at all. I think it might be a fuse because my car seems to go through a lot of fuses on the power accessories. The a/c panel fuse crapped out a few times as well. I'll check the motor when it stops raining here in NYC.

If the pump doesn't make any sound as the doors are locked or unlocked then it's probably an electrical problem as you suspect. There are 6 wires at the supply pump:

- black from the orthopedic seats (if equipped, what for?)
- red with black power from fuse (13?)
- blue from driver's lock
- green from passenger's lock
- yellow from trunk lock
- brown to ground

I doubt that you have to be concerned with the black wire since you probably don't have orthopedic seats... or a black wire.

The red wire with black stripe should see a constant 12V.

The brown wire should have continuity with the chassis/frame.

All of the lock wires should see 12V when the door is unlocked and continuity to ground when the door is locked. Any one will act as a trigger.

Good luck.

Sixto
91 300SE
87 300SDL
81 300SD