Hi everyone! I have read almost every forum I can regarding the 4WD system on this truck. I have replaced almost everything I can to try and get it to work but for the life of me can’t figure it out. Probably something simple at this point but I’m so frustrated I can’t think of anything else, which is why I am here hoping to get some insight from y’all.

I Have replaced GEM, replaced the 2 solenoids on the firewall (have good vacuum there now), replaced vacuum actuator(also has good vacuum), replaced the transfer case shift motor, replaced the 4WD switch and the transfer switch relay in the dash.

as soon as I turn the key on to the acc position the transfer case shift motor put the transfer case in 4WD low with the switch 2WD and no 4WD light on on the dash. Once I crank the truck and turn the selector switch nothing happens. wont come out of 4WD low unless i disconnect the transfer case motor plug and manually put 12v to it for it to reverse the motor and put it in 2WD. while the transfer case shift motor is unplugged and I move the selector switch 4WD the dash light will light up and lock the hubs, but this only
happens when the shift motor is not plugged in.

I am at loss and extremely stumped. Any ideas?

 

That is odd because the system is supposed to do a self test when you turn the ignition on and if everything is not correct the system should be completely disabled.

It sounds like it is disabling it correctly but something is going wrong in the self test and it is shifting.

Does it have the wrong shift motor? There's a lot of them that look exactly alike.
Or is the wiring for the shift motor messed up?

Quite possibly, the gem is bad.

 

Thanks for the reply mbb!

the GEM is “supposed” to be a functioning “refurbished” GEM. Everything that did not work with the old GEM is now working with this “new” one besides the 4WD. I bought the Dorman 600-802 electronic shift motor and transferred the brown wire to the correct spot. I just purchased another Cardone Shift motor to see if maybe by some miracle that would work 🥴.

 

Did you repin the shift motor to our trucks or did you just install it and plug it in? They are not plug and play with the reman's. There are 3 wires that need to be popped out and switched to another hole for our trucks. It will put in you low if you didn't repin.

 

akdoggie thanks for the reply! I did not repin it. I just swapped the brown wire from the transfer case over to the new plug. Do you know off hand which pins need to be swapped? I have looked at the old plug and compared to the new one and it seems to be the same as far as wire/pin location, but I have been wrong a few times in my life lol

 

 

I just watched that video. Other than the brown wire, I did not see him change the location of any other wire. He simply pulled the brown wire from the old plug and placed it in the new plug.

 

Update! Replaced the Duralast transfer case with a Cardone and wouldn’t ya know it the system works as it should! Crazy! I’m over this now 😂

 

Update on this: I ordered and replaced the transfer case motor, exactly as described in the video. Once removed the old motor I moved the internal lever from 4WD LOW to 2WD HIGH (with motor turned on and in neutral to ease up turning it) and then mounted back the new transfer case motor.

The truck was now correctly in 2WD LOW but had issues that the engine cut the power as soon you move faster than 30 mph, so I disconnected battery for approx 24 hours, on next start I heard a "click" from under the dash and now everything works fine, Seems you need to disconnect battery to clean up all errors and misreading from auto electronic and insure all reading are correct and let the GEM see coherent data and readings and properly configure everything.

So best option is purchase a new transfer case motor and change it, it's a quite affordable expense and can be changed with some effort (I did it by going under the truck, quite tiring because you have to work in a quite uncomfortable position but doable).