Service 4wd - Bad Encoder Motor Sensor?

corym1 · January 15, 2008

I've been seraching for the right answer to this broblem for months and think replacing the encoder motor sensor will solve it, but before doing so would like some confirmation based on the details below:

I've had the same experience as many others with my 04 duramax auto 4X4. One day the 4 low light lit up after ignition when it was in 2 hi. Soon after the "Service 4WD" message appeared followed by the check engine light. This has been hapening on and off for the past few months despite the following attempts to fix it.

-first I removed the 4X4 fuse in the cab to prevent and unexpected engagement

- next I replaced the 4X4 switch in the dash with no change

- I then pulled the TREC fuse under the hood, which did reset the system and put the 2 HI light on the switch back and got rid of the "service 4WD" message until I started the truck the next day and the same error resumed.

I've talked to some GM service manages that say the encoder motor likely needs replacing, but a friend (also a GM service tech) says only the encoder motor sensor needs replacing if the error code "C03-27" is found. I'm avoiding bring it into the dealer to pull this code for a $92 fee when I think I can get the sensor for around $100 and replace it myself. If anyone agrees that my next move should be to replace the sensor, does anyone have the instructions to do so? I have the 04 service manual, but it's not in there. Hope to hear from you soon....there's been a lot of snow this winter and not having 4X4 sucks!