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.
Sparky,
Thanks for all your help. Three years ago I bought a 1998 F250 and it had all the problems with the GEM as you originally described, windows didn’t work, dome light, 4×4…… I found this thread and Switched out the GEM and followed your write-up and it fixed all my problems. No problems for three years until this past week. So the new problem, I turn the truck on and everything works fine a few minutes pass and the 4×4 light comes on by itself High then low and goes off, I hear a click then the driver window stops working. Could it be that the GEM I replaced has gone bad? Happy new year by the way.
The GEM is a possibility but in your case I would recommend someone doing a lot of pinpoint testing to confirm the actual problem. A scan tool capable of reading GEM or CTM codes would make it much easier.
Hey I have a 2002 f150 and I have no wipers and no wiper fluid dome light on driver side does not work but passenger side does it has power windows but they all work. I have checked the motor and pump and both work and have replace the wiper switch
The very first thing to do is open the passenger door when the problem is present. If the GEM does not see a door open signal it will keep the accessory delay relay engaged for about 10 minutes.
My 1998 f150 4×4 key out of ignition and wipers, radio, and power windows still have power to them, now my shifter wont come out of park unless 4 way hazard lights are on. Replaced ignition cylinder, ignition switch, still the same. did your test on battery saver relay and both showed 12 volts. What could this be? Please help, signed Little Joe