Question: On my 2003 Ford Explorer, the power windows sometimes don't work. When one doesn't work, none of them do. I already replaced the switch in the driver-side door, but it didn't fix the problem. I noticed the switch in that door gets hot when the windows aren't working, but in a little while they start working again.
Answer: That all the windows aren't working means we're looking for a break in a power or ground source common to all four window motors. I pulled up the wiring schematic, and a red flag is the main power feed for the windows located at the battery junction box. That's the fuse block under the hood adjacent to the battery. Power to all window motors begins at fuse F1.6 -- 60 amp. But from there the current passes through a circuit breaker (30 amp, F1.47) before reaching the accessory delay relay, the driver's master window switch, and eventually the motors. Here's the most likely scenario from where I sit: One of the power window motors may be internally shorted and drawing excessive current (amps) when in use. Typically it's going to be the driver-side window, because that gets the most use. When operating the driver's window, the excessive amperage draw from the motor is tripping the 30-amp circuit breaker. A breaker, unlike a fuse, will reset after a short period and resume supplying voltage to the circuit. The fact that the master window switch is getting hot when the problem occurs is another clue to an excessive current draw. That the windows stop working while operating the driver's window also points us in the same direction. I'd hook up an ammeter to the driver's window motor circuit, and check for a draw near or greater than 30 amps. If that's the case, replace the motor while ensuring there are no physical obstructions of the glass, or perhaps a binding window regulator. Of course, there are other possibilities, such as a motor other than the driver's drawing excessive current, or a circuit intermittently shorted to ground. But this is certainly the place to begin diagnosis.
How To Reach Alex
If you have a technical question regarding your pickup, SUV, or van, feel free to contact Alex, a master technician with the National Institute for Automotive Service Excellence. Send a letter to him in care of Truck Trend Garage, 831 S. Douglas Street, El Segundo, CA 90245, or e-mail us at email@example.com. Please include the VIN with your question. Due to the volume of questions received every month, we cannot guarantee that everyone's question will be personally answered or will appear in the magazine.
Can't wait for help with a problem you're having with your Truck or SUV? Ask the expert we trust here at Truck Trend Garage -- visit Alex Steele at www.RealWorldAutomotive.com.