Hello all!

I've been having some trouble with my 4wd and got a lot of good info from this site but I haven't quite found what I'm looking for.

This truck is new to me and the 4wd didn't work when I got it. I would flip the dash switch but there were no 4x4 dash lights and no sounds from the transfer case selector motor. I did the bulb test at the plug to the x-fer case motor and it blinked and lit up properly when moving the dash switch so I replaced the motor thinking all was well, aside from the dash lights still did not indicate anything (they do light up when turning on the ignition so its not a bulb problem). We got some snow this week, I put in 4wd, locked in the manual hubs and low and behold, I can't get up the driveway, rear wheels spinning but no action from the fronts. I get it back into the shop and re-rerun the bulb test and this time, I've got nothing.

So I try manually grounding the control coils in the 4wd relays under the hood and I can run it from 2wd to 4wd down to low and back again. I checked and made sure that in 4wd the front wheels were turning and it works fine. I dug back into the dash switch and it has power at the plug and the switch has proper resistance in all three positions. I thought maybe the GEM is acting up, so I tested resistance to ground at pins 10 (bn/wh) & 11 (og/lb) and neither pin had continuity to ground in any of the dash switch positions. Is the GEM toast? Does anyone have diagrams for the dash switch control wires (I'm not sure if they go back to the GEM or over to the 4wd module).

Thanks for the help!

 

I have the same issue on an 07 superduty and will post back here if I find anything Cheers! I am looking for the same diagrams for my truck. It sounds like the GEM's are hard to get new so some people have found used ones and others have described simply re-wiring the 4x4 circuit so the GEM is not in play... This would however not be fool proof as it would allow you to engage 4-lo while moving, etc. Anyways I will post the diagrams if I find them back here.