Strange problem with driver side power window. The window will not go down when I push the switch. However, it will go down on its own,intermittently,while driving down the road. The window will go back up fine once its down. It will not go down with the switch though. The passenger window works fine. I have to believe its not the motor since it goes up fine. Any ideas would be appreciated. I have the Haynes manual which offers little help. Does anyone know where the GEM is located and the one touch power down relay. Also where the grounds are connected for this circuit. Thanks

 

Could be several sources for the problem.
1. Switch
2. Gem Module
3. One touch down relay
4. Wiring (likely in the boot area between the door and the A pillar)

The window switch is normally in a ground situation in the neutral position on both sides through pin 5 of the switch to Ground 200 black wire. When you switch to down Gem gets ground from pin 5 through pin 1 TN/LB to pin 8 of the the Gem Module and motor gets hot from pin 4 LB/Bk through pin 2 WH/BK to motor. Motor gets ground during down through the fuse box, through the normally off one touch down relay to ground pin 24 of the fuse box to Ground 200. When you switch to one touch down, Pin 3 Grey gets momentary hot from pin 4 LB/Bk and sends that to Gem at pin 9. Gem then provides power to the coil of the one touch down relay and activates the relay switch to the OG/WH wire from the Central Junction Box to the Down pin of the window motor OG/WH.Ground is now provided by the normally grounded WH/BK through the switch. Gem measures the resistance of the circuit and determines when the motor has reached the full down position and then swiches off the one touch down relay.

I would look for a sticking one touch down relay, switch, or broken wiring. Also the F150 from that year is notorious for water leaks from the windshield and you could be getting shorting in the Gem module which is mounted on top the fuse box or the fuse box is shorting itself from water contamination. The one touch down relay is in the same fuse box and also check that the accessory delay relay is in good working order as well.

Hope this helps.

 

Thanks for the info Homer. Bad news. I went out to do some troubleshooting with the information you gave me and the thing started working and has since. The weird part is the same thing happened last year about the same time of year and each time it was after it had rained and then froze the next day. Then when the weather warms up it starts working again. I don't know if its ice somewhere or whats causing it. But its hard to TS a working circuit. Any thoughts on this? Thanks

 

Well like I said these are known for water leaks at the windshield getting into the gem and fuse box. Also could be the motor itself gets water in it and freezes. Next time it rains look for water drips along the park brake lever area and the areas around the fuse box. You can remove the fusebox and look in it for signs of corrosion as well.