Power Window Motor (Page 1/1)
Cobra_Ranch_Garage MAR 07, 03:59 PM
I have a mystery that I just can't figure out. I appreciate any and all help solving this. 1986 GT.
My passenger side power window was slow and then stopped working. I cleaned both switches and still nothing. I checked to ensure power to the switch, good. I checked power coming out of the switch AND power at both the red and blue wire at the motor while operating the switch, again, good. So I ordered a new AC Delco motor from amazon. When I hooked it up it won't move. I grounded it and put a hot wire to it where the plug goes, nothing. I thought maybe it was a bad motor so I returned and got another one. Same result. The battery is charged and the other window works. WTF is going on? What am I missing.

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@ cobra_ranch_garage

Cobra_Ranch_Garage MAR 07, 04:19 PM
OK, so I had someone help hold everything for me and I was able to touch a wire to each prong and to the positive and negative terminal of the battery. The motor does move. So why won't it move when it is getting power to the switch and to the motor itself?
ArthurPeale MAR 07, 04:23 PM
Time to check everything mechanical in the operation. The regulator. The tracks - they can get gummed up. The rollers - ditto.

you can remove the motor from the door and place it on a small platform, still plugged in, and try and cycle the window - does the motor actuate?

I just got done tearing apart the door on my own '86 GT - I did it because the window would go up halfway and then stop.

My fault - it was binding on the dew wipe that I'd half removed.

It didn't take very much. I was easily able to move it out of the way and have the window continue upward.
FieroJimmy MAR 12, 08:40 AM
The question is: How did you test for power and ground at the motor? Did you use a multimeter, an LED test light, or an incandescent test light? An LED test light or multimeter will not load the circuits adequately. Even an incandescent test light may not load it enough for something with as high of a current draw as a window motor. A single strand of wire will light a test light, or test good with a multimeter, but when you are trying to draw several amps through the circuit you will have too much voltage drop. I like to use a headlamp bulb to test high current wring.

The first thing I do is hook the bulb up to both circuits I'm testing. In this case both terminals of the window motor connector. Then operate the switch up and down and compare the brightness of the bulb to what it is with a direct connection to the battery. In your case, one side or the other definitely has high resistance.



If you look at the schematic, you can see the motors ground back through the switches. Since we know there is a problem with one or both legs of the passenger side window wiring, you can hook the test light to the battery, and ground it through each terminal at the window motor. One side or the other should only dimly light the bulb.
Cobra_Ranch_Garage MAR 12, 09:36 AM
Thanks FieroJimmy. I just used a test light. I'll give this a try.
Cobra_Ranch_Garage MAR 24, 11:26 AM
To close this thread out:
I had tested the new motor on a battery and knew it worked so I installed it. Once every thing was in I cut the wires and wired a car battery directly to the motor. It went up and down just fine. I then twisted the window wires back together and used the switch, no joy. I had a tool to remove the wires from the switch and hooked the battery to them and the window again worked. So I at least knew the wiring was good from the switch to the window motor. I took the drivers switch out and hooked each wire to the terminals and it worked also. So bad switch maybe? But this bad switch was getting power to light up a test light before, but not power the window. So before I ordered a new switch I took the switch apart one more time to clean it. it was worth a shot? It then worked fine! I expect it may act up again and I'll just order a new switch. It's strange, the switch put power to the motor but wouldn't move it before and after a cleaning. I have no problem admitting automotive wiring is my weak spot and I probably went about this the long way. Oh well, at least it all works now. I hope this helps someone in the future. FYI. I just popped the plastic rivets off the bottom of the door and removed the side door skin bolts and had good access to the door internals and could pull and install the motor that way. Harbor Freight has the plastic pop rivet gut with the rivets for $17.99.
Mickey_Moose MAR 27, 03:23 PM
Voltage is only 1 aspect, the window motors are current driven and your windows switches may not be making a good enough contact to allow enough current to flow.

Because you measure 12v doesn't mean they will work.

Install Rodney's window helpers is a better way to go to eliminate the current needing to flow through the switches (or build your own using relays).

[This message has been edited by Mickey_Moose (edited 03-27-2023).]