I had a rebuilt HD transmission put in about 3 months ago. This past weekend I switched from 2wd to 4wd hi and got nothing. This is the first time I tried going into 4wd since I had the tranny replaced. I know the 4wd worked before I took it in for the tranny job. The guy at the transmission shop said it was the transfer case shift motor that went out, but would not accept responsibility for the failure and said these things go out all the time. It looks like a classic mechanic trick to me. Any thoughts?
This is a post I did some time ago on diagnosing transfer case shift problems. Because my truck is a 2004 and yours is a 2000, the fuse #'s won't apply, and when I talk about a 4WD control module, you will have a GEM module instead. However the rest should apply.
Thanks David! I checked the fuse inside for the switch and it was fine. When I took it into the transmission shop that replaced my transmission, the guy checked some relays under the hood. I do not know if the ones he checked were the right ones as my owners manual does not show those. He also said he could hear the shift motor trying to switch the transfer case, but couldn't, so he says it is the shifht motor that is bad. I just have a hard time with something that was working fine until it was removed and reinstalled by these guys and doesn't work now. Could they have tightened some bolts/nuts too tight? Could they have dropped the transfer case and damaged the shift motor without any visible damage to the outside? Thanks for your help.
The shift motor just bolts to the side of the transfer case and they shouldn't of needed to remove it, so I don't think it could be a bolt tightening problem. If they damaged it I think it would be visible.
If you can hear the motor trying to shift, there is a possibility that the encoder isn't working. The encoder is a set of switches in the shift motor that signals back to the GEM that shifts have completed and what position the motor is in. If the encoder doesn't detect a shift, the GEM will reverse the shift and it will sound like what you describe.
You might find the encoder connector (it's the 5 or 6 wire connector to the shift motor), disconnect it from the motor and inspect the pins. Make sure none are bent or corroded.
I also had my transmission rebuilt, when I got it back, my transfer case would not go into 4 low. It would go into 4 high. After pulling the dash loose to check to see if there was power to [Shift on the fly switch], it appears that the GEM Module going bad. The mechanic that is working on it said the Transfer case motor caused the GEM Module to go out. He told me that I should replace the Transfer case motor also, or expect to buy another GEM Module soon. I wish I had Manual 4X4.
The mechanic claims that the shift motor is going bad, and that it caused one of the diodes in the GEM Module to burn out. He said that he cycled the motor several times, it got hot and stopped working all together.
He let it cool, and it went back to working, only 4 high though. 4 low is still not working. The GEM Module should be in tomorrow.
The shift motor doesn't get it's power directly through the GEM, but through a set of relays. So the shift motor can't draw too much power from the GEM. I can see the shift motor getting hot and needing replaced. But keep in mind that it's not intended to be run continuously, but just momentarily. Long enough to complete a shift, which is maybe about a second at a time.
Thanks for the info, it makes sense to me. The thing that bothers me the most is just like in the original post, it happened right after having the transmission rebuilt. It all worked before, now it doesn't. The cost of the transfer case shift motor is not as bad as the GEM. I would hate to not have him change it and burn out the GEM again.
I took a look at the video, my situation was different. When I turned the ESOF switch to 4high the light would come on. When I tried to get into 4low nothing happened, NO light, No 'Clunk' from the transfer case.They started in the fuse box, and checked to see if there was power to the ESOF switch. No power at the switch. They replaced the GEM Module and now it works fine. The mechanic said that water caused the GEM to go bad, shorting out one of the circuits, the one for 4low.
If it wasn't so expensive I would have converted the transfer case and got rid of ESOF.