I had the same problem. The door locks and the power mirror. I also had a
non-operational rear hatch lock. All problems were traced to wire breaks.
The power door and mirror breaks were at the boot in the drivers door. The
rear hatch break was by the rear light. The wiring was very tight. A couple
extra inches would have prevented the break I think. I spliced in a
"relaxed" harness, a lot less tension at the boot. I had the same short wire
problem in the cruise control at the steering column. The wire pulled right
out of the connector. They must have had a wire shortage when my Westy was
built.

Bob Wing 88 Westy