W126 Door Lock Problem

[revray]

Aloha,

I have two 1982 300SD's. On one of them, the automatic door locks all work with the key. On the other, they don't. Disconnected by the previous owner... maybe for an alarm installation... but I'm not sure. I want to connect it and use it again. Here's what I've tried so far:

* Found plug to actuator in driver's door unplugged. I plugged it back in.
* I found fuse #15 missing. I replaced it.
* Swapped pumps to check function ~ pump is good.
* Swapped door actuators to check function ~ actuator is good.

I lock the drivers door with the key from the outside - no pump and the other three door locks don't budge. I sit in the inside of the car and depress the door lock knob - no pump and the three door locks don't budge.

I disconnect the yellow vacuum line from the pump in the trunk, hook up my hand vacuum pump, and with a few quick pumps, the driver's rear, passenger's rear, and passenger's front locks all go down (in that order).

I'm not sure what to do next, and would appreciate any tips you all might have.

Thanks.