When I unlock the drivers side door none of the other locks open. I have to manually unlock all the doors. When I use the key on the drivers side, I hear a noise (probally vacuum pump) in the trunk for about 10-15 seconds. Nothing happens. I know it's all related to the vacuum system, how do I isolate this problem to the cause? Thanks again for all the help.

1982 240D 225,000
1983 300DT 175,000
1983 300DT 160,000 great car
1986 300SDL problem child