Is the GEM and CTM one module or two on 1998 SOHC 4WD auto

[sehaare]

wipers, moonroof, windows all stopped working. Had to travel for work and have not had time to troubleshoot other than quick check of fuses. I took along the wiring schematics with me on my trip and I now suspect it is the GEM/CTM is that physically one module or two can't really tell from the schematics? Thanks

 

[sehaare]

I should be able to troubleshoot it for real tomorrow to eliminate a couple of relays that could also be the issue.

 

[410Fortune]

GEM module, switches and relays controls those things

what is CTM?

 

[1998Exp]

GEM module, switches and relays controls those things

what is CTM?

CTM = Central Timing Module. A name used by some automakers for a box with similar functions to Ford's GEM

 

[donalds]

 

[J_C]

AFAIK, there is only a CTM on lower level (lesser factory optioned) vehicles, maybe sports or some stripped down Rangers, instead of the GEM which when present does the CTM duty, so no (Ford of this era at least) vehicle will have both a GEM and a CTM, just CTM if the vehicle doesn't have features that need a GEM or vice versa.

I too would first look at relays, particularly the battery saver and accessory delay relays.

After swapping relays around with known good ones, if no luck then there are tests you can do to rule out the GEM. GEM just grounds the relay coils, so manually you could connect a jumper wire between the battery saver relay purple/orange wire and ground which should turn it on. Similarly you could jumper to ground a wire between the accessory delay light blue/red wire and ground to turn it on. I'd start with the battery saver relay both for swapping it and for jumpering to ground to test it because it has to work for the accessory delay relay to come on at all.

Frankly the eventual failure of the battery saver relay is common enough that I would go ahead and buy one to keep in the glovebox if it hasn't failed yet, given its age... they're about $10 on amazon. Example: Amazon.com : Standard Motor Products RY612 Relay : Automotive
Edit: Amazon's listing is screwy, select "AC heater switch and relay" even though that's not your purpose.

Local auto parts stores may carry a different brand or of course motorcraft with a different part #. Sometimes auto parts stores want near double Amazon's price. It should be in a box up under the dash near the driver's right side footwell.

There are different relay box configurations for different vehicle years. I guess I never got around to making a comprehensive list of what each model year looks like, but this pic below "might" be the right one for a '98.

Notice that the battery saver relay is the same type used for most of the other positions. You could swap the battery saver relay with one of those as a test.

 

[sehaare]

AFAIK, there is only a CTM on lower level (lesser factory optioned) vehicles, maybe sports or some stripped down Rangers, instead of the GEM which when present does the CTM duty, so no (Ford of this era at least) vehicle with have both a GEM and a CTM, just CTM if the vehicle doesn't have features that need a GEM or vice versa.

I too would first look at relays, particularly the battery saver and accessory delay relays.

After swapping relays around with known good ones, if no luck then there are tests you can do to rule out the GEM. GEM just grounds the relay coils, so manually you could connect a jumper wire between the battery saver relay purple/orange wire and ground which should turn it on. Similarly you could jumper to ground a wire between the accessory delay light blue/red wire and ground to turn it on. I'd start with the battery saver relay both for swapping it and for jumpering to ground to test it because it has to work for the accssory delay relay to come on at all.

Frankly the eventual failure of the battery saver relay is common enough that I would go ahead and buy one to keep in the glovebox if it hasn't failed yet, given its age... they're about $10 on amazon. Example: Amazon.com : Standard Motor Products RY612 Relay : Automotive
Edit: Amazon's listing is screwy, select "AC heater switch and relay" even though that's not your purpose.

Local auto parts stores may carry a different brand or of course motorcraft with a different part #. Sometimes auto parts stores want near double Amazon's price. It should be in a box up under the dash near the driver's right side footwell.

There are different relay box configurations for different vehicle years. I guess I never got around to making a comprehensive list of what each model year looks like, but this pic below "might" be the right one for a '98.

Notice how the battery saver relay is the same type used for most of the other positions. You could swap the battery saver relay with one of those as a test.

View attachment 321341

Thanks for the great reply. I had suspected those relays as well but i hadn't had a chance to figure out where they were located. I went ahead and ordered the relay as you suggested. You also cleared up the CTM/Gem question. thanks again

 

[sehaare]

View attachment 321339

Thanks for the reply, if I'm reading it correctly it implies that a Bad gem would only take out the "one touch" feature of the drivers side power window and not affect the other windows (and possibly let you manually put the driver window up and down by holding the button). So, since my other windows do not work (which I check again today when I get home) then it is probably not the gem, and I'm now leaning towards it being the power saving relay, but instead of guessing I'll get in and take some voltage reading when I get home to isolate it to the right component.

 

[sehaare]

Thanks again to everyone who posted, I'll be digging into this further after I get home (and of course watch the Bears game first)

Steve

 

[J_C]

Thanks for the reply, if I'm reading it correctly it implies that a Bad gem would only take out the "one touch" feature of the drivers side power window and not affect the other windows (and possibly let you manually put the driver window up and down by holding the button). So, since my other windows do not work (which I check again today when I get home) then it is probably not the gem, and I'm now leaning towards it being the power saving relay, but instead of guessing I'll get in and take some voltage reading when I get home to isolate it to the right component.

No, you have a GEM because the one touch down feature (in addition to other features) needs it to work, but the GEM also controls the battery saver feature through which all power (to some things) goes through the relays in question, so in theory a bad GEM could cause this but it is significantly less likely, and you could rule out the GEM with the test I proposed previously, that there are a couple wires going to it to activate the relevant relays and all it is doing is grounding those wires from the relays' coils so if you ground them yourself and the problem remains, it rules out the GEM. If you ground them yourself and the problem goes away, maybe it's the GEM, or a wire to it or whatever is supposed to be triggering the GEM to activate the relay(s).

 

[sehaare]

As a follow up (because I hate threads that just end without any info on what they found or what fixed the issue), while I was trying to figure out how to get the cover off of the relay module to get to the relays, I noticed that the interior lights had started working again. So I stopped and checked and everything was now working.

There is an old saying when working with electronics "you can't fix what ain't broke" which loosely means that you can't figure out the cause of the issue if the issue is no longer there. So intermittent electronic issues can be the hardest to troubleshoot.

But in this case I can rule out blown fuses, as they don't "unblow", and since I was no where near the GEM module (and I think some of its functions were always working and a partial failure is more unlikely) I don't think that the gem module was bad. BUT, since I was pushing and pulling on the relay module cover, I suspect that I had a stuck contact on either the accessory delay relay or the battery saver relay that by bumping the relay module around helped unstick it. So once I figure out for sure which relays those two are I will just replace them (I'll probably cycle the old relay's coils with 12 volts to see if I can hear the contacts opening/closing and keep those as spares) .

 

[sehaare]

As a follow up (because I hate threads that just end without any info on what they found or what fixed the issue), while I was trying to figure out how to get the cover off of the relay module to get to the relays, I noticed that the interior lights had started working again. So I stopped and checked and everything was now working.

There is an old saying when working with electronics "you can't fix what ain't broke" which loosely means that you can't figure out the cause of the issue if the issue is no longer there. So intermittent electronic issues can be the hardest to troubleshoot.

But in this case I can rule out blown fuses, as they don't "unblow", and since I was no where near the GEM module (and I think some of its functions were always working and a partial failure is more unlikely) I don't think that the gem module was bad. BUT, since I was pushing and pulling on the relay module cover, I suspect that I had a stuck contact on either the accessory delay relay or the battery saver relay that by bumping the relay module around helped unstick it. So once I figure out for sure which relays those two are I will just replace them (I'll probably cycle the old relay's coils with 12 volts to see if I can hear the contacts opening/closing and keep those as spares) .

Here are the relay positions for a 1998 if anyone ever needs them