"sevice 4wd"

CKUBIK · December 10, 2008

to whom this may concern:

I own a 2006 GMC crew cab 4x4 vortecmax. bought the truck new and use as everyday driver, the truck now has 44,000 miles on it and im having issues with the the 4wd. I have had the truck to the dealer (Flannery Auto Mall bad axe mi) once before for trans seal replacement and some leaking oil cooler lines and leaking timing cover seal. i have since experieced a service 4wd message multiple times. the first time i drove it about 10 miles with the message on and the indicator lights not lit up and that time i noticed no power when i tried to accelerate. i got it to my destination and when i started it later to move it i noticed the indicator lights came back on and stated that the differential was in 4wd lo. I pushed the 4wd hi button and the diffential made the usual clunk when it disengages and then i shifted to 2wd hi without issue. at the time i thought i may have pushed the button by accident and disregarded. i then talked with a mechanic friend and he suggested i try to replace the dash switch. i replaced the dash switch with a new one and thought that my issue was resolved. shortly after the message reappeared when i started the truck so i simply shifted it again and it was resolved. i contacted the dealer and explained the situation to them and they advised me to bring it to them and get it scanned by the tech 2. i couldn't take it right in due to the distance from home and work so, i thought i would wait until i was in the area. then on friday november 28th i had the issue again. this time with limited power again. this time i put the accelerator to the floor and could only get the engine to rev to about 2400 rpm and accelerate very slowly. i drove 1 mile and pulled over and turned the truck off and back on and again the switch said it was in 4wd lo, i shifted per the manual to 2wd hi and the issue resolved again. immediatly i called the dealer and they advised me to bring it in. i drove to the dealer and when they scanned it they found no stored codes and when we drove it and looked at it could find nothing wrong. 3 hours later i experienced the service 4wd light come on with no indicator lights but the truck drove as if in 2wd without issue for 2 hours straight. once i arrived at my destination i once again resolved by turning off and back on again. i have since had the issue 2 more times and corrected it myself by turning off and back on again and shifting per the manual. if anyone has any insight or fixes to the problem i am experiencing please help.

thanks

corey kubik

CKUBIK · January 31, 2009

hey everyone just an update my truck is still having the same issues as described in previous, but i was gettting an oil change done at a friends tire shop and as i was pulling my truck onto the lift the code came up so we scanned it and i got a code of C0327 Encoder Circuit Malfunction. I believe it may be a bad encoder sensor, but am not sure. If any one has any tips please send me a message. Thanks and good luck to all that are having the same issue.

thanks corey kubik

jbordi · February 1, 2009

My 05 silverado has done the same thing. The encoder motor sensor was replaced at about 45,000 miles. The sensors are a common problem with these trucks. I have read where some people have replaced theirs about every 20,000 to 30,000 miles. You can get the part at GM parts direct for about $80. You may want to see if there are any service bulletins for your 06 truck regarding this issue.