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GEM module replacement

aldive

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I think I have a fried GEM.

Apparently its not a plug and play replacement. The following is from Alldata:

>>Prior to removal of module, it is necessary to upload module configuration information to New Generation STAR (NGS) Tester. This information needs to be downloaded into the new module once installed.
Electronic modules are sensitive to static electrical charges. If exposed to these charges, damage may result<<

then after install:

>>To install, reverse the removal procedure. CAUTION: Once the new module is installed, it is necessary to download the module configuration information from the New Generation STAR (NGS) Tester into the new module. NOTE: When the battery is disconnected and reconnected, some abnormal drive symptoms may occur while the vehicle relearns its adaptive strategy. The vehicle may need to be driven 16 km (10 mi) or more to relearn the strategy.
<<

So this not a DIY replacement and must be dealer done?????

Thanks for any assistance.
 


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CougarX

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Those who have done an electric shift 4406 swap in their V8s have swapped out their stock GEMs with GEMs from a V6 with no reported adverse effects. I believe if you get a brand new GEM from Ford they come unprogrammed and therefore must be programmed to your vehicle/drive train combination. However, if you get a used GEM from the same year Explorer with the same engine and drive line (2X4 or 4X4) then it should be plug and play. For the 98 and older models I believe the speedometer worked through the GEM somehow(the GEM was programmed with the tire diameter), but I'm pretty sure that they changed it to the ECM in 99 and up Explorers so that all it controls is interior accessories/switches/etc.
 




aldive

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I have lost control of the power windows ( all ), the radio, the puddle lights, the overhead lights, the speedometer and the tach.
 




CougarX

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That definitely sounds like a GEM. Like I said though, if you get a used GEM from a 2wd (you have 2wd?) 99 SOHC it should be plug and play. The only variable would be tire size if indeed that is still controlled by the GEM on 99s, which it sounds like it is if your speedo doesn't work. But, if you have stock sized tires then the used GEM should also be correctly programmed. Any of the SCT tuning guys should be able to tell you if the tire size is in the GEM or ECM for a 99. If they can adjust for tire size in a tune then its ECM controlled, if they can't then it's GEM controlled.
 




aldive

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Tire size on my '99 is adjustable via SCT's Advantage III software.
 




CougarX

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Looking at the wiring diagrams for the GEM from my 99 service CD it looks like the GEM gets signal from the ABS module which it then turns around and sends to the ECM. So that would explain the speedo not working, even if the signal is modulated and converted to a speed by the ECM. I don't see anything going to the tach though, nor do I see a connection for the radio at all. The courtesy lights and power windows are both controlled through the PCM though.

<EDIT>
"The courtesy lights and power windows are both controlled through the GEM though."
 




IAmTodd

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Eric swapped his when he did his V8 swap. And that was into a two door and everything works fine. I would imagine putting a two door GEM into a four door would have some adverse effects though.
 




budwich

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this is probably a "dumb question".... but why were you replacing your GEM in the first place?????????
 




IAmTodd

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Post #3.
 




budwich

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oh I thought that was the result of replacing the GEM... not the reason TO replace the GEM. Anyways, if that's true.... I would say your problem(s) have nothing to do directly with the GEM itself but "things" going to the GEM.... just my thought.
 








gijoecam

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IIRC, somebody had a similar issue once before... Let's look at what they all have in common:

Windows: Accessory delay relay fed from Fuse #4 (30A) in BJB, and that relay is controlled by the battery saver relay, fed from Fuse #26 (aoA mini) in the fuse junction panel.

Radio: Depending on whether or not you have the high series console...
-In the fuse junction panel, #20( 7.5A), 28 (7.5A) and 29 (25A)

Puddle Lamps: Controlled by the GEM module, via the battery saver relay.

Overhead lights: Battery saver relay, fed through the interior lamp relay, again controlled by the GEM

Speedo: Instrument cluster, fed from FJP #25 (7.5A), the speed signal is fed from the 4WABS system, in conjunction with an input from FJP #11(7.5A)

Tach: Again, FJB # 11 (7.5A) with a ground signal from the PCM.

Now, if we dig back a little further, we see that the radio circuit, PATS, Instrument cluster, and portions of the GEM are all fed from the battery saver relay. Fuse #11 is fed from the ignition switch.

All the roads seem to be pointing back at a major power loss in the main battery junction box, or the GEM. We can rule out the GEM if the problem persists after that, so I'm leaning towards either one of the MAXI fuses being blown, or the battery saver relay stuck open.

I need some more time to pour over the schematics, but check it out and let me know....

-Joe
 




aldive

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Joe, I was definitely hoping that you would chime in to this thread.

Where is the battery saver relay?
 




aldive

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I found the diagram, but am not sure where it is located?
 

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aldive

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Joe, does a new GEM have to be dealer programmed? I have conflicting info on this?

Thanks ....
 




aldive

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I went out and checked fuse # 11 in the FJB and determined it blown.

Cranked the truck and once again had tach function. A short test drive determined the speedometer functions restored.

Many thanks, Joe.

Now on to diagnosing the remainder of my GEM related woes.
 




aldive

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Joe, you are indeed the Ford man.

After reading your most helpful post, I tracked down fuse # 26 in the FJB as my problem; it was indeed blown.

After replacing that fuse, the windows worked again ( you don't realize what a pain in the arse it is to not be able to lower the windows until you loose that feature ). The overhead lamps function as well as the puddle lights.

I do not believe that I have a GEM issue after all.

All thats left to troubleshoot is the radio. Its an aftermarket Alpine CDA-9883 and I believe its problem is in the adapter connector.

Joe, thanks again; you are truly a major asset to this board.
 




budwich

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wow it amazing that fuses have such an impact... :)
 




gijoecam

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wow it amazing that fuses have such an impact... :)

Crazy, isn't it? :confused:

Happy to help out, Al. :)

________________________________________________________________
Now I'm wondering... did all these problems happen at once, or did they start dropping one at a time? If it was one at a time, that would explain why I couldn't pin it all down to a common issue. If they were all at once, I'd be curious why and, more importantly, how it happened?...

As for the location, I can't find my service CDs for the 99 MY at the moment, but I believe that relay block is in the passenger compartment, below and to the right side of the steering column. I *think* you remove the knee guard and they're on the upper right side, but don't quote me on that. I'll try and remember to take a look at the service manuals when I get to work in the AM.


Also, as for the stereo issue, tell me which stereo you had in the Ex originally, and whether or not you had the high line console (i.e. rear controls) so I can look at those schematics again tomorrow. There are, IIRC, three fuses for each of them, and they varied depending on which console you had.

The first thing I would do is pull the unit and check the connector for hot power and switched power at the appropriate pins. (Again, need to check the schematic for color) Those are the two critical wires, and most of the rest are just speaker wires. My guess is you're either not getting the switched power, or you blew the fuse for the main power too.

-Joe
____________________________________________________________________
SIDE NOTE: ALWAYS CHECK THE FUSES!!! I was 14 when I learned that lesson I'll never forget. I spent a Sunday afternoon playing apprentice to my father and grandfather working on grandpa's '87 Dodge Caravan (which later turned out to be my first car). We spent the better part of 5 hours replacing the passenger side window motor because grandpa had that problem once before, and it was a bad motor. They spend all that time getting it swapped out, and low and behold, the new one doesn't work either. So me, being the smart-alec I am, said, "Did you check the fuse?" They looked at me, looked at each other, and their expressions said it all. A few "I thought you did"'s and a 5 cent fuse later, and the window remarkably ran up and down, as did the old motor which they tried out just for fun.

When we sold that minivan a decade and 100,000 miles later, that motor was still in a box of extra parts sitting on the shelf in my dad's garage.

That's how I learned my lesson: ALWAYS CHECK THE FUSES FIRST!!!
 


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aldive

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Other than the radio issue. I will fill you in later, Joe., the parking light illuminate whenever the ignition is on.

Any more ideas ( or have I used up all my favors?> ).

Thanks ....
 




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