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.
My drivers side window on 1997 F150 only goes up, not down. I replaced the motor & controller. Same result. I checked voltage going to motor at disconnet in door and going up, get 12VDC, going down only -8.60 VDC? Bypassed switch in door same result, so I don’t think the switch is at fault. Per your article I checked Voltage at GEM, between terminal 85 & 86 and get 12 VDC. Replace battery saver rely with new relay, no change. Any ideas?
hey sparky ive got a 2003 ranger 4×4 4.0. recently my battery has been dieing over night. i replaced the gem module with no avail. my dome light has been unhooked for quite some time now. i just noticed the cargo light is not working but havent tried to us it in a long time. when i removed f2.11 fuse from the fuse panel inside the passenger compartment which controls the instrument cluster, main light switch, 4 wheel drive control module, central security module, gem, fuel tank unit, they all quit working(which was assumed) but the door chime begins to work. any ideas on where to look next?
Your truck uses a Central Security Module and not a GEM, so it is safe to say that the GEM is not the issue. I looked over the diagrams and found that the horn and cruise control work independently of the CSM, so the CSM will not be a part of those problems. The CSM is a major part of the door lock system but there are also a ton of other components. Not sure what kind of testing you have done but you will need wiring diagrams at a bare minimum to do testing.
Sparky my 03 f150 has lost power locks, cruise, and horn. I did all tests and have the right voltage everywhere…have had water issues before is it safe to say I need a new GEM?
If they can deal without having wipers and a dome light then yes they can wait. I water intrusion is a factor, the water issue needs to be addressed as soon as possible.