In this thread https://www.ford-trucks.com/forums/1...oor-locks.html I learned that the GEM (generic electronic module) controls the power windows. Mine are randomly quitting, for a day or so, then they come back. 2000 F-250 XLT 7.3 (see sig).

Today I got another weird symptom. The Edge Insight console lit up when I opened the driver door! The Edge is only supposed to come on when the ignition is on. My master tech friend said broken insulation in the door hinge area could cause that, but we looked at the loom there and it looks great. No visible breaks and the rubber is still flexible.

I wonder if my GEM is going south, and it's monkeying up both the power windows and the Edge. We used the Edge to check codes, but it has no codes logged. I learned here that the GEM can get water in it in early Super Duty trucks because it's attached to the back of the fuse box, so Ford moved it in 2002 to a safer spot. We put a new windshield in this truck, so no leaks now, but perhaps it was leaking earlier.

Does the GEM have to be programmed to the truck when you put in a new one? I found a post on PowerstrokeNation where some poor guy replaced his GEM without flashing it into the truck, and his truck went wacky like a wolverine on meth. He'd switch on the ignition and the starter would engage immediately, for example.

Edge Insight II console:

 

Yes it is likely that the GEM is going bad as its chock full of relays. my 99 7.3 had a windshield leak water got there and it would also do weird things like turn on my defroster without the key in the ignition and try to start itself randomly. Definitely get it replaced before it causes shorts in wires and such and possibly start a fire. I replaced mine with the exact model code that was on it.

 

If you're only having power window issues I would definitely consider pulling the GEM and fuse box and seeing if there is moisture/corrosion inside, but I wouldn't automatically assume that the GEM is bad. Usually when they go bad, there are multiple symptoms, windshield wipers being another very common one.

If you end up needing to replace the GEM, you need to get one with the same code number printed on it or you'll have all kinds of issues.

Yes, the windshields on these trucks are well known for their leaks.

 

Thanks guys. We'll pull it and have a look. My master tech friend also wants me to reinspect the door wiring loop very closely at the door jamb side.

 

I would think if it's only window issues, that it's more than likely a bad wire in the loom, years of opening and closing the doors break wires. You have to inspect each wire closely, it may look good on the outside but could be broken on the inside, I went through the window issues on my 95 F250 and it was all in the drivers door

 

We got the fuse box, GEM, and computer out. No corrosion or traces of water infiltration. Unplugged and reseated the GEM a few times for good measure.

So the only remaining causes, logically, would be wires in the door jamb, a failing GEM, or Russian spies.

 

If you don't see water or corrosion, I think that basically seals the deal that you're looking at a wiring issue for the windows alone. Again, when the GEM goes bad, it usually takes a lot more than windows with it. And the general cause of them going bad is water infiltration. You don't have water infiltration. Look elsewhere.

 

Thanks guys.
We did a closer inspection of the wiring loom at the driver door. Both sides of the bellows come off easily and are flexible. The wires in there are also flexible and we didn't feel any variations in the feel of the wires that might reveal a broken wire inside the insulation.

In another thread I saw a mention that the power door lock switches daisy chain, such that just one bad switch can foul up locking for all doors. I already pulled, opened up, and inspected the driver door power lock switch. It could not look better, might have been replaced already. If the truck acts up again, I'll remove and disassemble the front passenger door lock switch.

If the problem doesn't come back, perhaps reseating the GEM connectors helped. They look like they are a copper alloy, with tinned connecting areas on the flat sides, and copper visible on the edges. Probably pretty spendy stuff.

 

 

I think my GEM has been bad for ages. I had the power lock problem, and solved it for awhile using the foil trick. Which might have toasted the GEM, I don't know. Eventually I replaced all the actuators with aftermarket ones that work much better. Some years ago they stopped working too. The aftermarket keyless alarm still works, but the doors never lock.

As I recall the GEM is buried in the dash, and expensive to replace. Which is why I've never bothered to fix it. I think the lock actuators are okay, they're just not getting input from the GEM.

Early '99, but I don't think I've ever had a windshield leak (?)
I'd like to fix it if it's a reasonable job.
c.

 

 

I'm glad to hear that advice again. Only the door locks are acting up. This was a one-owner truck, and we don't get a heckova lot of rain in Texas, so our GEM has apparently never been wet.

 

Hey guys, the door locks are acting up again today, inoperative, but occasionally will lock with the button. No problems for 6 months. To recap, we've

1. Removed the GEM and looked for water damage, found none
2. Cleaned up the multi-contacts and used tiny amounts of conductive copper grease
3. Inspected the wiring loom in the driver door jamb and in the door, they look fine
4. Inspected the driver door power door lock switch, it looks new, clicks fine
5. Today I inspected the passenger door power lock, it looks OK, clicks fine (see pics below)

So your advice would be to open and inspect the back door switches now, rather than order a GEM?

I'm old so those small points in the switches remind me of ignition distributors. But they way the switches are built is pretty clever, such that they snap open or closed, reducing any micro-arc time. The passenger door switch is dusty but not inside. A little green on part of the copper suggesting water was in there at one point. But the green is not in an area that would affect its operation.

Do those resistors fail? If it did, would the switch ever work again? I bet I'll go out there tomorrow or the next day and the power door locks will be working again, for a day/week/month.

 

I think you're doing a little too much "inspecting" and not nearly enough testing. Get out a voltmeter, use the diagram from the thread you linked from, and actually test the window switches rather than looking at them and guessing they're okay because they look "clean". It can kind of cut it really early on perhaps, but at this point you've done a lot of looking and nothing "looks" all that bad. Time to start getting a little more in depth. Perhaps some continuity testing at the door jam wiring as well...

If you had access to a GEM with the same code as yours and you could test it for free I'd say absolutely give it a try. But finding one with the same code can be tough and they're not that cheap. I know it sounds easy to throw some parts at it, but if you're gonna start throwing parts, start with window switches for all 4 doors before you jump to a few hundred bucks on a GEM that also "looked" fine don't forget.