Service 4wd Message

[dakota29]

2006 Silverado, Vmax 6.0 gas.....

 

I know there is a problem with the service 4WD message popping up. What is really causing this??? Sometimes when I start my truck and start to go, it is in 4WD LOW....... automatically.....??? Anyone else seen this?????

 

 

[Blake]

Pics of your VMax or you're lying

[Matt_]

Likely the encoder motor sensor... C0327 will be the code if you get your code history read.

 

$70 in parts... an hour or two in your driveway if you are decent at turning a wrench. Or $600 for a complete shift motor assembly.

[hoot29576]

I had this problem in an 06 avalanche, it was repaired 5 times, everything had been replaced but would still do it. Mine got to the point where it would lock in neutral and wouldnt go anywhere and a few times it would kick into 4low while on the highway.

 

I eventually had to get rid of the truck, GM never could fix it nor were they willing to help me any.

[Adster]

My '04 Sierra got steadily worse after time with this message eventually coming on all the time and starting up in a random mode (4hi/lo/auto).

 

Started by replacing the control switch, then the electronic shift motor assembly (couldn't buy just the encoder), then the 4wd control module, then the PCM. Each time would seem to fix it for a while but would eventually come back just as bad.

 

Eventually replaced the wiring harness from the control switch to the transmission and that got it. Still not cheap though for the whole harness. So it wound up being wiring. Son of a bitch of a problem that doesn't seem all that uncommon on the '01 - '07, GMT 800's.