Service 4wd... 2003 Duramax

[JoeRags]

2003 GMC 2500HD. 6.6 Duramax/allison with 100,000 miles. For a while now the "Service 4wd" message comes and goes. Had it scanned a while back and no code. Did some research and found that many people have problems with the pushbutton transfer case selector switch going bad. Replaced that today and I'm still having the problem. "Service 4wd" comes on sometimes, other times it does not. Also, sometimes the selector switch is telling me I am in 4 low, sometimes neutral, all while I am clearly in 2wd..

 

Anybody else experience this? Terrible experience last time I brought this truck to the dealer, so I'm hoping its something I can fix.

 

Thanks,

Joe

[ColoradoSkiCountry]

Did you reset the computer when you replaced the switch? Did you get a new switch? You'll want to disconnect the battery cables for about 30 min or so, touch the battery cables together (make sure BOTH batteries are disconnected) If it still does this after doing that then I'm going to guess there is something else going on.

 

 

Ryan

 

 

2003 GMC 2500HD. 6.6 Duramax/allison with 100,000 miles. For a while now the "Service 4wd" message comes and goes. Had it scanned a while back and no code. Did some research and found that many people have problems with the pushbutton transfer case selector switch going bad. Replaced that today and I'm still having the problem. "Service 4wd" comes on sometimes, other times it does not. Also, sometimes the selector switch is telling me I am in 4 low, sometimes neutral, all while I am clearly in 2wd..

 

Anybody else experience this? Terrible experience last time I brought this truck to the dealer, so I'm hoping its something I can fix.

 

Thanks,

Joe

[JoeRags]

No dice... disconnected both batteries for 30 mins or so. Drove around for a while and the "service 4wd" message is back. I replaced the transfer case selector switch with a new unit from the dealer.

 

Now, when I powered the truck back up, the engine oil life indicator is still at 0% (as it was prior to my attempt to reset the computer)... should this have returned to 100% after the computer was reset?

 

Does touching the battery cables together have anything to do with the reset, or is this just ensuring both batteries are disconnected?

 

Thanks

[ColoradoSkiCountry]

I've been told that touching the two together helps to discharge any left over power in the system. It seemed to help on my old 99. It won't reset your oil life monitor as that is hard set in the computer. If touching the cables together does not help, perhaps you can go to Autozone or one of the autopart stores that can read codes and see if they can reset any codes in the system. If the lights are still comming on after that, then either you have a bad switch, or the T-Case has some SERIOUS issues. New switches have been known to be bad from the factory and sometimes idiot customers will return a bad part in the new part box in an attempt to get $$$ back.

 

 

No dice... disconnected both batteries for 30 mins or so. Drove around for a while and the "service 4wd" message is back. I replaced the transfer case selector switch with a new unit from the dealer.

 

Now, when I powered the truck back up, the engine oil life indicator is still at 0% (as it was prior to my attempt to reset the computer)... should this have returned to 100% after the computer was reset?

 

Does touching the battery cables together have anything to do with the reset, or is this just ensuring both batteries are disconnected?

 

Thanks

[Bluedog]

2003's were notorious for issues with the TC encoder module. GM issued a software change, and then put out a new part to fix the issue. IIRC the encoder was relatively cheap, and fairly easy to install.