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.
Hi sparky- thank you for great post. I am having exact issue- no wipers, door chime,dome light, cargo light-but will work intermittently. I have manual windows and door locks so no issues there. I followed your test procedure and showed 12v between bottom r slot and top r slot with battery saver relay removed. I removed gem per your great instructions and found no corrosion or evidence of water intrusion anywhere. Put it all back together and and everything worked again until the next morning and nothing again! Do I have a short somewhere that would cause all these to work, then not work? I dont want to buy a new gem if it is not my problem(or is it still?) Thanks for any help- i need my wipers!!!
You of course will need to do the testing as outlined in the repair post. I have gone back and added a link to the repair post on how to actually change the GEM.If you reread it you should now see the link.
Sparky my name is John i have the same problem with my 97 f150 no windows work no wipers no inside light please tell me how to fix it
I would like to say that I am a genius but the simple truth is that time has taught me to consult a wiring diagram and follow the KISS theory (Keep It Simple Stupid). The two biggest hinderances in automotive electrical repair are a lack of information and over thinking the problem. I have the information be cause I use Mitchell 1 information systems. I keep it simple by starting at the the highest load part of a system that I can easily access. The switch is easy to gain access to and I quickly found that there was no power on the light blue/black wire. Following a wiring diagram I knew that I had to go to the battery saver relay for two reasons. One to confirm that that the relay had power and two to jump the relay circuit and determine if there was a relay control problem or a broken wire in the driver’s door jamb. After jumping the relay contact terminals I knew that the wiring to the switch was okay because I could now operate the window. Kept it simple. Now I had to move on to why the relay would not perform it’s function. Testing showed power to the coil so logic would dictate that the ground circuit (which according to the wiring diagram is controlled by the GEM) for the relay coil was missing. Again keeping it in simple and direct test steps
A friend pointed me to this thread, and I must say that I am impressed! OK… I am not a professional mechanic, but I have spent a fair amount of time helping others troubleshoot their cars. Some things that would flush this out as being more instructional so that followers may be able to figure some things out on their own are: How did you know to go to the battery saver relay to check for power there, and why? also to check the quality of the ground there, and why?