Crazy Electrical issue!

[ffej]

Jeff Here, 97 Expedition 4.6. With headlight switch ON, Drivers power window will not operate. What in the world could be happening? Also, intermittently when the headlight switch is switched on the idiot light cluster in the lower right instrument panel flashes on and a warning tone sounds. Any ideas?

 

[riphip]

That is not one of the years with windshield leaking water is it??

 

[Gary Waugh]

I would be suspecting a bad earth connection to the control units, the headlights take a lot of current and that will cause all sorts of strange things to happen when a bad ground connection is present. I would get a piece of wire attach one end to a good ground connection and then touch the other end to grpound connectors on the control boards and even headlights and see if the windows start to operate. this will then give you an idea of which ground connection is not working properly..