I posted about a week ago and received some good feedback, but the central locking system of my 1983 300SD TurboDiesel is still failing. When I turn the key on the drivers door, which should activate all the other doors, trunk, and fuel door, the drivers door opens but nothing else does. I checked fuse 13 which controls the central locking system and it's good. When I remove the fuse and then put it back, I can hear the pump in the truck activate, and it automatically locks any door that I manually had unlocked. The trunk is locked so I can't check on the pump. I was told that the switch on the drivers door carries power from a blue wire for lock, and a yellow wire for unlock. I'm not sure what to do next. I can't get the fuel door open and I'm running out of fuel!