Just purchased a 1978 Bronco for a plow truck, the window motor failed to work for the nine years the previous owner had it. I've pulled the motor and replaced the plastic pins the motor turns when hooked directly to a battery. I've orderd a new dash switch (should it be a momentary, the old one would stay in either postition you put it?). I think the safety switch in the tailgate has already been bypassed (wires taped together near gate handle)? And what fuse powers that motor? I can't find it listed in the owners manual. Thanks for all the info already. TB

 

No fuse- circuit breaker at starter solenoid.

 

Yes, it is a momentary switch, it is spring loaded to the center position. The power for your rear window will start on the hot side of the starter relay. There are two wires that are both black with white strips, one goes to the accessory safety relay and the other goes to the tailgate key switch. With you ignition switch to accessory or to the on position take a test light and see that you have 12 volt power to the blue-black wire on your dash mounted rear window switch. If you don't have power there check your accessory safety relay and see if you have 12 V power on the blue-black wire there. If not check the black white wire for twelve volts, remember the black white wire is the one directly wired to the starter relay and should have power. If there is power to the B-W and none to the BL-BK then the problen will be a bad relay or broken wire to the relay. Also I have seen the tailgate key operated switch go bad and prevent the power from the dash mounted switch from going through it. Let me know what you find and I can help you more if needed. I have the wiring diagrams for the 78 Broncos.

Michelle

 

The rear window motor operates off the same fuse that the door locks run off of.

-Matt

 

sorry mathgewc i dont agree with you , there is a circut breaker not a fuse.otherwise if the windows got frozen in the winter you would be blowing out fuses all ythe time.

 

Re-read the original post, saw that his is a 78. My bad. Just know that on my 84, the rear window and door locks run off the same fuse.

-Matt