I have an 01 F250 with a 7.3 and 4x4 with ESOF. I have been having issues with the 4x4 for going on a year now. I hit the switch and it will not shift. The 4x4 light on the dash does not come on at all, not even when I first start the truck. At first I thought the issue was related to the GEM as that had been changed in the past. So after some significant effort and cost I got a new GEM and installed it. This solved some of the other issues that I was having but still no 4x4. So the next potential culprit was the transfer case motor. So I got a new one and installed that and still nothing, no change and no 4x4 light on the dash. We checked all the fuses and relays before I bought the new GEM so the only possible remaining cause that I can think of its the wiring between the GEM and the transfer case motor. Has anyone on here had any similar experiences with this? How do I test the wires and most importantly does anyone know where I can find a wiring schematic for the 4x4 system to help me test the wires? Any help would be appreciated!