HELP!!! W123 power window problem...

[dugudas]

hello all, im having some serious problems with the power window on my 83 300D... the drivers window will not roll down, period. i have searched on here and believe i have exhausted all threads on this. i pulled out the motor and it will roll up but not down, i tried an extra motor from a door i bought for parts and same issue... rolls up but not down. i cleaned all switches (which were very dirty/corroded) and tried the switch on another window, switch is good. i pulled the wires (1 green and 1 black) through the door tunnel and into the car by hood release and found no breaks in wires. what else could be the problem??? anyone? please help! thank you all.

[BillGrissom]

With the door panel off, isolate the 2 wires to the motor. Connect 12 V to the wires, trying both polarities. One polarity should make the motor move the window up and the other move it down. If so, your motor is OK. I can't imagine why it would turn only one way. It is a simple DC motor so swapping leads should reverse direction.

If it works both ways, that suggests your "switch is good" statement is incorrect, or could be a bad wire from the switch as well. I have fixed several "bad switches" with a few sprays of contact cleaner into the innards. To test what the switch & wires are doing, connect a multimeter at the motor terminals (with motor wires removed). In fact, don't start any electrical diagnostics without a multimeter. They cost $0.00 at Harbor Freight w/ coupon.

[dugudas]

i have tried the switch on passenger window and it rolled up/down without a problem... apparently it has to be in the line from switch... i checked the normal spot (little tunnel from door to car) and no visible problem. i will go get a mutimeter today and see if that points me in the right direction. thank you for the help!