GEM module? Got any wiring diagrams?? - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 3 (permalink) Old 03-14-2014, 11:42 AM Thread Starter
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GEM module? Got any wiring diagrams??

Vehicle: 2004 Excursion PSD
Problem: I have no freaking clue! lol
Symptoms: Well, the first thing I noticed was I started the truck up and the environmental controls weren't working. Nothing lit up, not responding, etc. Everything else worked fine. So I turned it off and restarted. Everything was fine. A week later the same thing happened to the radio. Did the same thing, and it's worked fine ever since. Last night as I was backing into my driveway, I realized I was at the normal distance from the garage (won't fit in there) and yet the proximity sensor alarm wasn't yelling at me. Of course I thought it was just off somehow so I push the button. Nada. The light says OFF, but when you push it, nothing changes. Try a couple times, no result. Then I noticed the illumination for the auto 4WD go out. Today I have no problem with it though.

So in doing my research I have read about a lot of people who have weird intermittent issues and it's generally the GEM or VSM. Think it's called a VSM anyway. Anyway, they always had multiple things wrong though. Radio is out and windows don't work as well as something else.....or heater controls don't work as well as wipers and the dash cluster. That kind of thing. So that kinda leaves me wondering what the heck my issue could be. I figured I would try to trace the power wires in a wiring diagram to see if they had a common source or separate power relays or what, but I can't find a schematic anywhere. On this site all I can find are specific diagrams like for the gauge cluster, or heating system, not a general entire dash diagram.

So, does anyone know where I can find a schematic I can use? Or has anyone encountered something similar and have any ideas? BTW, absolutely no water leakage into the cab and the fuse box and GEM (at least what I assume is the GEM) have zero corrosion on any of the terminals.
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post #2 of 3 (permalink) Old 03-15-2014, 02:21 PM
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Re: GEM module? Got any wiring diagrams??

Yeah, It sure sounds like the GEM. And like you said usually it is caused by water damage. You should be able to open the GEM up and look at the circuit board also, see if you see and water damage.
You can probably get a wiring diagram from a online library, in Michigan we have it, but you have to enter you Michigan drivers license number to get in.
So the first thing I'd be looking at is too see if everything that is giving you problems is tied to the GEM, if so then it probably a safe bet that it's bad.

2015 Challenger HellCat Redline Red 8sp
1997 F350 4X4 CCLB PSD
2004 Jetta TDI
1999.5 Jetta TDI 11mm pump S7 PP764's 3bar MAP
1986 F350 CC Dually 6.9 ATS turbo lowered
1984 Mark VII 2.4 BMW Turbo Diesel
1970 Roadrunner 383 4sp
1970 Cuda 426 4sp Dana 60
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post #3 of 3 (permalink) Old 03-19-2014, 08:58 AM Thread Starter
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Re: GEM module? Got any wiring diagrams??

Haven't gotten around to checking for water damage. Did look at the library. No good. But, I ordered a set of diagrams on a DVD so I guess I'll see what I can find when it gets here.
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