Thanks for the feedback.

@RANDY P - how you describe the connections in your first post is what I have tried. I haven't tried grounding the violet and violet/black lines yet though. i also need to test the actuator to rule out a faulty unit.

@cypress - the 85 300D doesn't have any built in actuators for the central locking. You have to add an aftermarket actuator to the driver door lock. Unlocking/Locking the driver door is what signals the vacuum system to unlock/lock the rest of the doors.

However, i did read in the manual that the system has built in relays, so I have tried connecting the Green/Black and Blue/Black wires from the brain directly to the aftermarket actuator, but that hasn't worked either.