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.
So, the relays are kicking in once the power is restored…but why is it the power is missing from the 85/lower right terminal. I get absolutely no voltage, except on occasion when it clicks and things decide to work again for a minute. Sounds like this is a moisture, power wire, or grounding issue more than a GEM issue? Thanks again for your help!
Assuming your truck is laid out like the one in this repair article, terminals 85 & 86 would be the top and bottom right terminals,the two smaller sized terminals. A solid power and ground on those two terminals would make the relay click in when installed. When the relay clicks in, terminals 30 and 87 are bridged inside the relay. That sends power to the power window switch.
I’m having a similar issue. 97 F150 with 5.4L, 2wd. No windows, dome lights, and wipers intermittently work (more often not lately). This started with the windows, the the rest came later. Removed relay #2, checked for voltage: 12v on bottom right, 12v when jumping across terminals 85/86. I have no power to the window switch. When I pull the 1st relay (top left) I have no power from the bottom right terminal. The relays check out, function and resistance. All fuses inside and out check fine. The only water leak I can find so far is from the back window. From time to time I hear the relay clicking and things work like normal, then click, and back off. Is this a bad GEM, or a separate issue? Thanks
The GEM does not control power to the power outlets or the lighter.
Thank you so much. Does GEM control power at outlet?
Sergei