Hello,

I've read many posts about this topic, but there was some confusion amongst the posts and what I see in my doors doesn't match the consensus.

The consensus that I found is that on the W126 there is a vacuum/pressure pump in the trunk. From this pump there is a single yellow tube that connects to all doors except the driver's door. In the driver's door there is an electrical connection that instructs the pump to either supply vacuum (locks the doors) or pressure (unlocks the doors).

All of this matches my car except the driver's door description. My driver's door also has a yellow tube and a vacuum locking pod. I believe that what happens is that all of the doors (and the trunk and the fuel door) are controlled by the vacuum system. The electrical switch in the driver's door simply signals to the pump to supply vacuum or pressure, which locks or unlocks everything (including the driver's door).

Now, assuming my description is correct, does anyone know what electrical device is in the driver's door? I have found three wires which appear to run towards the driver's door external handle; but all three have been cut. There is a brown, a red with white stripe and a green wire. To me this would appear to be the wires that ran to the electrical switch.

Should I try shorting the red wire to the brown one, and alternately the green wire to the brown one to try the vacuum pump/system? To what did these wires originally connect? I would like to try and restore the original central locking system functionality. The vacuum pump does work (in both directions) and all of the vacuum circuit functions.

__________________
Mike Frederick
1986 300SDL, 240K+ miles
1985 300D KaliKar, 270K+ miles