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Ask Kenny Z. Your Own Question
Kenny Z.
Kenny Z., Ford Senior Master Tech
Category: Ford
Satisfied Customers: 5447
Experience:  Auto Trans, Drivability and Electrical Specialist
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2000 ford expedition: motor fuses relay..electronic..module

Resolved Question:

2000 ford expidition checked wiper motor fuses relay and changed multi-function switch and wiper still dont work. could it be the generic electronic module?
Submitted: 5 years ago.
Category: Ford
Expert:  Kenny Z. replied 5 years ago.
Hello and thanks for your question.

It very well could be but its next to impossible to confirm without a scanner that can communicate with the GEM module such as a Ford IDS or Snap On Modis. I have included the pinpoint test for this symptom below. You want to begin at pinpoint test A. There are several steps that can be accomplished without a scanner that might be able to identify a fuse or wiring concern. If you need any further assistance or have any questions please don't hesitate to ask.

Customer: replied 5 years ago.

you sent me a lot of info. I now basic stuff that i all ready have performed. please simple fye away i can check for problem. another thing to mention the back of the suv was rear end two weeks ago wipers in front wear sill working at first. could have the switch turned on shorted out something if the rear wiper switch was momentary turned on? front and back fuses are all good still

Expert:  Kenny Z. replied 5 years ago.
If the fuses are good then there is more than likely not a short as they are there to blow to protect the circuitry. You can see by test procedures that I sent you that this system is very complex and can't just be "simplified" to make diagnosis easier.
Customer: replied 5 years ago.
I looking at wiring diagram in haynes repair manual. Is there power going through the multi- function switch that i can test for? there is a main wire that ties all funtion together is this the power wire/
Expert:  Kenny Z. replied 5 years ago.
To briefly explain the system function, the wiper switch sends a switch position signal to the GEM. The Gem receives this signal and sends voltages to the proper relays which power the wiper motor. So you have the GEM, relays, and a ton of associated wiring that could cause this issue. Getting a code and running the wiper self test with a scanner would really narrow down the possibilities because the scanner can show what the gem is seeing as far as switch input, relay position and wiring continuity between the relays, GEM and wiper motor.
Customer: replied 5 years ago.

So If i understand this correctly. with out a scaner there is no way to test between the switch and the relays. because of the GEM is not as simple like test the motor or relay or fuses and the basic switch?

Expert:  Kenny Z. replied 5 years ago.
That is correct for the most part, When a scanner is attached the scanner sees what the GEM sees and monitors what the GEM commands. The GEM is also able to monitor voltage drop on most of the circuits in the system. Even if you were to check the wires individually and they showed good you don't know if the GEM is seeing the correct signals without being able to monitor it. Obviously you could go and check each wire blindly and if you found a bad circuit you could repair it and recheck. But at this point you wouldn't even know which wires to start with. The GEM controls many other functions on the vehicle and if they are working then its safe to assume the power and ground supplies to the GEM are good which makes it even more critical to have a scanner.
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