After 3hrs of searching post after post and not finding any help I am throwing myself to the mercy of the ESOF gods. My better half wants the ESOF so I cant convert it to manual shift like I did mine. I have no power going to the ESOF switch, lights on dash come on when keyed on like they should but dont come on when turning ESOF, no noise from shift motor, fuses checked and relays checked and replaced, ( took every relay and fuse from mine and switched with hers) shift motor is working fine with outside source. Tried to use test light to check for power to switch and that blew fuses, truck would not start and everything else seemed to quit. Traced it to the GEM smoked, replaced the GEM everything is now working again and back to original issue with ESOF switch. Any ideas or thoughts? I am afraid to use test light again as the GEM is not cheap. Almost forgot truck is a 2000 CC 7.3 6spd 150,000 and stock except for the hubs converted to manual and vaccuum lines plugged. Any takers with thoughts or ideas are very much appreciated.

 

Did you not answer why you get probs? Already manual with vac lines plugged!

 

He still needs to have the ESOF switch to work. The manual hubs means he needs to physically lock the hubs outside and then use the ESOF to engage the transfer case.To the OP:
I have mine set up the same way. I haven't had the ESOF issue with the dashboaerd switch but I am sure someone will give you some pointers. Especially if you say the dash oights up and doesn't engage, someone will help. This website is great. LOTS of good advice.

 

What is GEM? Do you have any type of DMM? If so do a continuity check from fuse to motor. I'm going to look for some wiring now, but in the mean time, is the switch hooked up to a relay? If so check the relay.
Yea totally missed you switching them out.

Is their just relay's though? Some of the info I looked at pointed out solenoids, but nothing I found points to your generation of truck, still trying to find a real wire diagram. But I would still emphasize doing a continuity check for the shift motor, and also clutch motor.

 

Well several more hours of checking wires and relays, pulled shift motor off and works fine on bench. Works fine on the truck when supplying power at the connector. I have tried to find wiring diagrams to use but cant find anything that is helping.
I really think there is a wiring issue but cant find the right circuits.
Does anyone know where I might find wiring diagrams that besides the ones I have in my Haynes and Chiltons manual.
I went and bought two new relays and started to replace every relay one at a time. Still nothing seems to work. I have taken every connector apart and inspected, cleaned, and put electrical spray on every module. I took the switch and swapped out with my truck this morning and it still would not work. Both switches work in my truck, both shift motors work in my truck.

 

Attached is the pertinent wiring diagram.

Here are some things to try. First, check all the fuses shown in the diagram with a test light. Check the bases to make sure the fuses are connecting properly.

Second, put a test light between the two wires at the shift motor. Not between a wire and ground. With the key in RUN, have someone turn the 4WD switch. You should see flashes on the test light as the relays attempt to move it.

If you don't see flashes, you either have a bad relay or the GEM module isn't trying to close them. The relays are usually two identical relays in a single auxiliary relay box under the hood. There are no other relays or fuses in the box and the box is generally wrapped in fabric electrical tape from the factory. You MUST have 5 pin double throw relays in there. There are 4 pin single throw relays that will fit but they won't provide the ground path necessary.

If the relays check out, then you are left with checking the continuity between pin 85 of the high to low relay to ground. You'll notice that pin 86 (one side of the relay coil) is always powered and the GEM grounds pin 85 to provide a complete current path and energize the relay. This grounding only occurs for a brief second or so, so you'll have to watch it with a DVOM carefully while someone does the switching.

If it doesn't appear that the GEM is grounding pin 85 like it should, then the GEM is bad, or it's remotely possible that the switch is bad or the wires to the switch are bad. If you get that far I can find a diagram for the switch. The switch switches 3 difference resistance values on two wires to the GEM. It's very simple.

 

David, I don't mean to hijack the thread but I am facing similar problems with my ESOF and was hoping you could help me out.

Here is what I have so far;

* I have power to my ESOF switch (dash switch), checked with DVOM on all settings and got the appropriate voltage readings for each setting
* Both relay's have been bench tested and appear to be fine.
* The transfer case motor works when put on another vehicle
* My dash switch will operate another transfer case motor on another vehicle
* I checked every fuse in my fuse box and all are good

I just read on your post for the first time just now about checking the brake pedal sensor so I will do that asap. I did check the codes and had a B1483 - "Brake pedal input open circuit" come up. Could that be my problem since the brake has to be depressed for the transfer case to shift??

The other thing I ask is could you explain better this part of your instructions?

"If the relays check out, then you are left with checking the continuity between pin 85 of the high to low relay to ground. You'll notice that pin 86 (one side of the relay coil) is always powered and the GEM grounds pin 85 to provide a complete current path and energize the relay. This grounding only occurs for a brief second or so, so you'll have to watch it with a DVOM carefully while someone does the switching."

Do I leave the relays in their sockets and test using the exposed wires under the relays? I have a fairly decent Craftsman DVOM, what setting do I use to do this test?

Also, here are three other codes I got when I checked. I must note though that when I scanned for codes the transfer case motor was not on the truck so none of the wire connectors were attached.

P1812 Transmission 4-Wheel Drive Mode Select Circuit Failure


P1865 Transmission Transfer Case Contact Plate Power Short To Ground

P1876 Transmission Transfer Case 2-Wheel Drive Solenoid Circuit Failure


Another important thing to note that when I noticed I could not shift the transfer case, I removed the motor from the transfer case, removed the black cover from the motor and it was full of water. I am thinking that when I attempted to shift the transfer case while it was full of water I may have shorted something or burnt something up which may be the problem.

Sorry for the long winded post but I wanted to give you every detail I could. I have been fighting with this problem for well over a monthand am about to go nuts and take it to the stealership!

Thanks in advance for any help!!