I own a 2004 GMC Yukon with push button 4wd. I bought the vehicle in Southern Arizona after receiving a work transfer to Northern Vermont. My problem started during my first winter in Northern Vermont. First, the “service 4wd” light continually came on. Second, my push button lights did not light up and my 4wd ceased to work. I checked my fuses and everything seemed to be okay. I took it to the dealership and they hooked it up to there computer systems and it said that nothing was wrong with the 4wd. The problem keeps happening. And now, the Yukon sporadically clicks into 4 low. Please help me.
Find a new dealer ,You will have a code stored.
I have a 2002 Tahoe with the same system.
First, check the front differential fluid level.
These vehicles have a common fault with the soldered connections behind the transfer case control switch.
Pry and pull the switches out (they all remove at the same time) and clean up (use an electrical contact cleaner) and check the connections, they may need to be re-soldered.
You have to remember the transfer case has a few second hesitation when switching from 4WD to 2WD. This is common with GM 4x4s.
Other faults MAY be coming from the Transfer case shift motor (on transfer case) or perhaps from the Transfer case control module (this is located behind the headlight switch, left of the instrument panel).
Note: This vehicle also has a Neutral switch which allows the vehicle to be towed without any damage.
To engage Neutral, push both the 4lo and 2hi buttons at the same time, and hold for ten seconds. A RED Neutral light will come on at the switch.