This 1997 Ford F150 came in with three complaints. The power windows do not work. The wipers do not work and the interior lights do not work. Figuring that they were all related I decided to test the easiest system to access, the power windows. I pulled the driver’s side power window switch assembly up and checked for power at the light blue/black wire with the key on. No power.
I then went to the interior fuse box and removed the battery saver relay. It is the small relay second from the top left corner.
I checked for ignition power on the lower right terminal, 12 volts, good.
I checked for ground at the upper right hand terminal by first placing one lead of my voltmeter to a positive battery source, 0 volts, bad. That in itself is enough to show that the GEM module is faulty but I also looked at GEM data with a scan tool and saw that internal system voltage was 22 volts. Hard to do with a 12 volt battery. Diagnosis of a faulty GEM module. To see how to replace the module please click here.
This is the reading with a new GEM module across terminals 85 and 86. Just like it should be 12 volts. Another important note is that I asked the customer about water leaks on this side of the truck and also closely inspected everything as I disassembled looking for signs of water intrusion. Water leaks are a big problem with these modules.
Again with the new GEM installed there is now power on the light blue/black wire.
In case you have not already figured it out if the windows had to be operated to raise a downed window you could do one of two things if there is no power at the light blue/black wire. One, you could apply 12 volts to this wire with a jumper wire. Two, you could jumper terminals 87 and 30 together at the battery saver relay. The second will also test the wiring in the door jamb as well.
Does your truck have a keyless entry pad on the driver’s door?
hey there sparky. im experiencing my cargo, courtesy, dash and headlights coming on when nothing is activateing them. this always happens during inclement weather while the truck is only sitting with no key in the ignition. in summer it will only last a day or two after the weather clears up but now in the cooler months its become considerably more persistant. now to the point where the lights come on while driving. i have also noticed the instrument cluster flickering and things getting to the point where it disrupts the theft system and not allowing the truck to start till after i disconnect the battery. could this be the GEM module or should i look further?? i have already inspected the 3 large plugs on the firewall on the driver side and packed them with more elec. grease. i disconnectedthe headlight switch while the system was malfunctioning and saw now difference. any thoughts??
thank you.
ed k.
For Anonymous: I have a serious issue with my 1997 f150, my
Driver power window will only go up… I had the exact same symptoms with my 1997 F150 a couple of years ago. Ended up it was a broken ground wire in the drivers door jamb. That was one of your suggestions to check. This is my first time here and I plan on bookmarking for future reference. Thanks.
Pull the door panels and check for switched power and ground at the window motor wiring harness. Keep in mind that in the neutral position there are no circuits at the motor. Connect your test light or meter between the two wires and check for voltage when the switch is operated. This will test power and ground at the same time.
Yes there is power and the ground is at the switch.