2006 Gmc Sierra "service 4wd"

[rctrex]

I have a 2006 Sierra 1500 CC with 75,000 mile. The Service 4WD message on the DIC. This started last spring along with the lights on the switch going out. Back then I took the switch out and apart. I cleaned the contacts on the switch and did not have the problem since. But with the cooler temperatures this fall it restarted, but the lights on the switch stayed on. I went ahead and replaced the switch, but I am still getting the message. It just stays in 2hi.

 

I called onstar and asked them to run the diagnostics to get the code, but they said there was no code returned.

 

I have read many treads on this site about replacing the encoder motor or the transfer case motor or different wiring harnesses. Can someone give me advice on where is the next most logical check since the truck is not showing a code? Thanks

[zaac]

Do not buy an encoder until you know for sure it's the problem. Up here in Canada the dealer wants $705 and aftermarket is $360. Sorry, that's all I can help.

[rctrex]

I called Onstar again to see if they could get a code, of course nothing showed up but then they transferred me to a diagnostics advisor and he said that Onstar will not pull codes from the transfer case. So I had a local shop check it for me and it came back with CO327-Encoder switch. So now I know what to replace, but I cannot find the part #. The local dealer wants over $600. Does anyone know the part number or where I can find it? Thanks!

[grampadirt]

I called Onstar again to see if they could get a code, of course nothing showed up but then they transferred me to a diagnostics advisor and he said that Onstar will not pull codes from the transfer case. So I had a local shop check it for me and it came back with CO327-Encoder switch. So now I know what to replace, but I cannot find the part #. The local dealer wants over $600. Does anyone know the part number or where I can find it? Thanks!

 

Check this out @ AutozoneEncoder Motor,hope it helps

 

Gary