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Okay, I have been doing a little reading and diagnosing of my 4x4. I have the Hubs Manually locked so the whole not having vaccum to activate the hubs is a non issue.

First of all when I turn the 4x4 switch no light on the dash comes on, so I did the norm, checked the fuses Relays and such, so then I Decided to go to the source and removed the T-Case Motor. I removed this and manually shifted it into 4H, when I got back up into the truck I noticed the 4x4 light was still off. From what I read if you manually switch the 4x4 on at the transfer case the light should come on, but low and behold I do have 4 wheel drive, I just get no dash light. So at this current time I have to crawl underneath the truck to activate the 4x4.

My what makes the light on the dash illuminate? And where should I go next to fix my ESOF
 

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A good scan tool like a snap on may help diagnose the problem. The GEM module controls the relays under the hood that control the shift motor on the t/case. Somewhere in there the chain is broken and you need to find out where.
 

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Ford could yes, probably AE too, Gotta ask, not questioning your intelligence or anything, LOL, have you checked the basics? (Does your light work when you turn the key on? During the "Bulb check" on the dash?) Do you have 12v at the motor when you engage the ESOF switch? If you have 12v down there, then the motor must be shot. I am not sure where the "Micro switch" that gets activated when 4x4 is engaged is at. If it is in the case, or someplace on the motor arm? Make sure you have 12v, in both positions of the switch, (Low/hi) Make sure you have a good ground. Ect...
 

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Discussion Starter #5
Yep, 4x4 light comes on during start up and then turns off in a few seconds like normal. I pulled the T-case motor and applied 12v and it would rotate clockwise and counter clockwise depending on which way I applied the positive and ground. So I assume motor is working fine.

I checked for 12v at the site of the motor when I turn the 4x4 switch and did not get anything.

Is there any way to by pass the relay and force 12v to the T-case motor from under the hood? The would at least tell me if I can do that, then the wiring connections is still good and then I could focus my effors to sensor that tells the GEM which location the transfer case is in or the GEM its self.

So can I by pass the relay under the hood? If so how?
 

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I would make sure you have power to the relays first. Power and ground actually and make sure you get the right relays. Its the two that are by themselves in a box.
 

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Discussion Starter #7
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SMOKESKULL</div><div class="ubbcode-body">I would make sure you have power to the relays first. Power and ground actually and make sure you get the right relays. Its the two that are by themselves in a box. </div></div>

Which position on the relay do I check for power (30, 85, or 86)? The other question I have when the relay is activated is the relay sending 12v to the T-case motor or ground?
 

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Has anyone solved this issue yet?

My dad has 2003 F-250 crew cab FX 4 with a 7.3 and found out that his four wheel drive did not work when trying to pull a flatbed gooseneck loaded with hay out of a wet hayfield, no light, no 4x4.
When I turn the switch, there is vacuum to the hubs. I got out a multi-meter and found that there is power to the big plug that goes into the side of the transfer case, but no power to the little motor on the tranfer case. I've checked all of the fuses, and, I pulled out the relay that supplies power to the motor,the two of them are identical in that box so I switched them just to see if that would do anything...nope.
Does anyone have any idea what is further upstream of that relay, and that could potentially be causing the problem.

Thanks in advance.
 

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I have the same problem going on right now. I have replaced the GEM module, the relays, the motor on the transfer case, and traced the wires all the way to the fire wall. I keep getting the "p1876 transfer case solenoid circuit failure". Ford dealer cannot tell me what to do about it. They cannot fix it. Paid them $1256 for all the new parts and it still does not work. I keep having to use a wrench to lock in my 4wd!!!
 

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My problem was resolved by the ford dealer. After messing around with it for about a two months. We took it in, there was no trouble codes. After an hour and a half they traced it to the wire that goes through the fire wall had cut itself on the firewall $90 and a butt connector and 4x4 works again.
 

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We have looked and tested and tested and looked a little more. The wires are all good from the firewall to the transfer case. Has to be something in the dash.
 

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Be aware that the dash switch has both electrical and vacuum connections and may need to be checked. Mine failed last year but had different symptoms than you are seeing. When idling (out of gear), mine would switch back and forth between 4-hi and 4-low. I could hear the transfer case motor switching and the instrument cluster light would also switch back and forth. It turned out to be a defective dash switch. Not sure if this has anything to do with your problem; just wanted you to be aware that it is switching both electrical and vacuum functions.
 

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The computer tests the switch function and it works. It also tests the dash light and it will come on. There is only one plug on the back of the dash switch and it is all fine. It is some kind of communication error between the transfer case and GEM module...just do not know where it is at or how to find it.
 

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Hey guys,

I've just bought a 2001 F-350 crew cab long bed and have been reading through all the threads about the ESOF. The transfer case motor is not engaging on the truck. The guy I got it from says he's replaced the GEM module and the dash selector switch. I checked under the hood and there are 2 sets of small boxes. Each has 2 relays in each box. I swapped the relays between the boxes and still not working. Anybody know which box is for the 4x4 and what the other one may be? Thanks!!
 

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The box in front of the fuse box is for the ESOF relays, and the one on the inboard side is for Battery Charge and Trailer Backup Light relays.

If the guy replaced the GEM and didn't get it configured for ESOF, that could be the problem.
 

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Today I checked the connections on the relays for the ESOF and checked the connections on the shift motor on the tranny. When I turn the switch between 4x2 and 4x4 HI, I can hear the relay clicking. If they are clicking, could that mean that the switch and GEM module are sending power to the relay? From there, is it just the motor itself to be checked and could be bad? Thanks!
 

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Had someone bring me in a transfer case motor. Changed it and thankfully now its working!
 

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Okay, I have been doing a little reading and diagnosing of my 4x4. I have the Hubs Manually locked so the whole not having vaccum to activate the hubs is a non issue.

First of all when I turn the 4x4 switch no light on the dash comes on, so I did the norm, checked the fuses Relays and such, so then I Decided to go to the source and removed the T-Case Motor. I removed this and manually shifted it into 4H, when I got back up into the truck I noticed the 4x4 light was still off. From what I read if you manually switch the 4x4 on at the transfer case the light should come on, but low and behold I do have 4 wheel drive, I just get no dash light. So at this current time I have to crawl underneath the truck to activate the 4x4.

My what makes the light on the dash illuminate? And where should I go next to fix my ESOF

Even if the switch is in 4x4 or you manually shift the transfer case into 4x4 high or low, the light will not come on until the GEM module see's the shift motor in either 4x4 mode. The motor has 4 on/off circuits that indicates whether or not the motor is in the correct position. Not until it is in that position will the light come on. If the GEM notices a fault in the system like a faulty vacuum hub solenoid, it will not attempt to move the shift motor. It is best to have the system diagnosed by checking for any DTC's under a self test and active command the shift motor and monitor each of the plate pids for proper position.
 

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Be aware that the dash switch has both electrical and vacuum connections and may need to be checked. Mine failed last year but had different symptoms than you are seeing. When idling (out of gear), mine would switch back and forth between 4-hi and 4-low. I could hear the transfer case motor switching and the instrument cluster light would also switch back and forth. It turned out to be a defective dash switch. Not sure if this has anything to do with your problem; just wanted you to be aware that it is switching both electrical and vacuum functions.

There are no vacuum connections to the 4x4 switch. It is electrical only. The vacuum hub solenoid under the hood controls all vacuum to the hubs.
 

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SMOKESKULL</div><div class="ubbcode-body">I would make sure you have power to the relays first. Power and ground actually and make sure you get the right relays. Its the two that are by themselves in a box. </div></div>

Which position on the relay do I check for power (30, 85, or 86)? The other question I have when the relay is activated is the relay sending 12v to the T-case motor or ground?
Both relays are naturally grounded to the motor. Once a relay is energized that relay then will apply power to that circuit. The other relay still has ground and the path is complete. To reverse the shift motor the other relay will be applied to provide power and the other one will be turned off to provide the ground back thus reversing the shift motor.
 
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