One of my friends decided that he wanted to install his own alarm in his 93 400E benz. He mis-understood how to wire up vacuum type door locks. He located the wire he thought would control the lock switch only, and tried to test it by touching that wire to ground. Now all of his locks dont work unless he uses the key in the trunk.
I dont have much experience with vacuum type door locks and the only resolution I could think of was to check all the fuses. We found a blown fuse under the hood and replaced it and still no luck.
Does anyone know if there is a quick fix for this or is this something that needs to be repaired at a shop?
Your friend broke the first law of auto-electrical work, grounding a wire without knowing it's function or using a buffer such as a snap-on testlight. Use yellow wire from trunk, check fuse position for corrosion on terminals-very common, its possible that the switches on both front door pumps have failed but unlikely. If vehicle has earlier 1 wire system, it's blue on the right, green on the left and yellow from the trunk. These wires change polarity on lock and unlock.
Just to complicate things, if your fusebox has Littlefuse plastic blade fuses rather than ceramic, you have a two wire neg system, leads coming up under leading edge of front seat (driver side) to join main loom going front to rear, black lock and hold for window/roof close, blue unlock, latch the door, remove and disconnect door contact, remove key and for God's sake go to ground through a test light.