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Q: Ghostly, seemingly unrelated electrical stuff

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Hi, With my '02 ford explorer, the gas gauge doesn't work, nor does the 4 wheel drive, it tries to stall when the headlights are on and the left blinker is engaged. I was thinking it could be the GEM. Do you know if a faulty GEM could affect any or all of these things?. Thank you!

My car has 200000 miles.
My car has an automatic transmission.

A: Hey there. The GEM (generic electronic modu...

Hey there. The GEM (generic electronic module) module could be the culprit with the headlights and turn signals. Simply unplugging it and starting the car should answer this question. If it still stalls, then you have successfully ruled out the GEM module. Expect a few systems not to work with the module unplugged.

The fuel gauge does not utilize the GEM module, so this will be a wiring problem, the fuel level sending unit in the fuel tank or the gauge on the dash. The same goes for the four wheel drive. The GEM is not involved with it. So the short answer is the GEM does not affect all of those systems.

When a vehicle stalls when electrical circuits are turned on, that should not be a part of the motor running - it is always a short to ground somewhere. Shorts are random and may not be in the circuits you have mentioned. The best methods to locate a short is to begin by diagnosing the easiest problem that affects the running of the motor.

As far as the headlights or the turn signal. Check to see if both front the high and low beams operate correctly and the turn signals are working. If not, begin by diagnosing these two systems. You will need a test light and accurate wiring diagrams. There is one variable you need to be aware of in regards to the wiring diagrams. There is an early production and late production. You need to check your production date and choose the applicable diagram. You can find the production date on the door jamb of your drivers door.

The four wheel drive and fuel gauge systems will need to be diagnosed independently of each other. It is possible, there is a common ground for all these systems. The GEM modules included. Usually, but not always, beginning with one problem will reveal how they are all connected. If not, you have more than one failure and they all need to be diagnosed independent of each other.

To have this taken care of, I recommend having a certified professional from YourMechanic, diagnose the stalling issue and electrical problems in person. Be sure to leave a note for the technician explaining under what conditions the car stalls.

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