Switch is to be suspected
should have it checked for codes
as encoder motor is a common failure with a similar symptoms

Answered by BMRFIXIT (expert)
19,736 answers provided

I was hoping for a little more insight than just "check the codes". The codes can be very misleading, not to mention expensive to get from the dealer. Is there no other test to isolate the problem between the switch (which now is illuminated again) and the encoder? What about a software update? Pulling out the TCCM fuse? Is "check the code" the best you can do?

Response from papanicko
1 question asked

I have a 2006 Sierra 1500 Z71 and my push button 4WD was acting up and it always said service 4WD. So I just replaced the switch and now its working great. It cost me about $90.00.

Answered by Hunter
0 questions asked

This problem turned out to be the encoder ring, not the switch and not the encoder motor. Pretty easy to change out, with good instructions on the web.

Response from papanicko
1 question asked