Service 4wd Light Cp327

dynodog62 · December 16, 2008

I have a 2005 GMC Sierra 1500 and I have been having the service 4WD light come on. The first was probably a year ago, then ever couple of months for maybe a week at a time the service 4WD light would come on. So last week it start coming on again. Then one night after work the it showed on the panel the transfer case was in "neutral" pushed the 2H and I could hear it shift into 2H. The next day after work, showed it was in 4L, pushed the 2H and could hear it shift again. So, had an appointment at the local friendly gm dealer for new tires and had them check it out. And the write up description on the bill says.....

"test system, fault CP327 transfer performance fault, isolate fault to range sensor in transfer case actuator defer"

So they said they need to split the case to replace the sensor, $100 for parts and about $250 for labor (2.2 hours)....

Now about 2.5 years ago I had service 4WD light issues, and at that time it had a CO327, that was the encoder motor sensor shorted. Sensor was replaced in a short amount of time, I was just in for a oil change. Didn't have any problem with it til now....

In my research I haven't been unable to find anything about a CP327 fault

To my question......Is there indeed a CP327 fault or is a typo on the bill? If it is a typo and they meant CO327, is encoder motor sensor and range sensor the same thing? Or are they both generic faults that could lead to any number of sensors? Are they a bunch of idiots at the dealer?

I just don't know how GM's fault system works and don't want to get the run around from the dealer. I didn't even know there were any sensors inside the case. I haven't had it fixed yet, but I have an appointment on Friday....

Please Help and Ease my PAIN!!!!!!!

5Alive · December 16, 2008

The letter "P" is adjacent to the letter "O" on every QWERTY keyboard, and that fact coupled with the symptoms you describe, combined with the fact that while there are P0xxx DTC's and C0xxx DTC's, there is no such thing as a CPxxx DTC, all leads me to believe that there is a typo on the work order estimate. I would assume that the intention was to type C0327, and you already know from experience what that means.