We are finally supposed to get a few inches over the next couple of days...just on the edge of the storm that is moving across the northern US. Pretty late for our first lasting snowfall of the season...if you don't count the 2 ft dump we had Oct 10!

Yes, it was the switch on the dash. I think it started working on its own again for a while, but I eventually had to replace it. Each button changes the resistance through the switch and causes the TCCM to command the various TC motor/encoder positions. If the commanded position on the Tech 2 does not change when you press the switches, then the switch is likely bad. If it does change, then problem is in another component. Not that we all have Tech 2s.

 

The switch module comes out as a unit. Pretty easy to replace:

Set park brake
Turn key to run position
Put shifter in 1st and tilt wheel all the way down
Pull off dash bezel
Release tabs that hold the module in place
Unplug module
Repeat in reverse order to install new module.

 

In my experience on the few vehicles I have seen with including mine it ended up being the connector going into the back of the switch. For some reason the wire crimps going into the connectors come loose. Its easy to check just pull the switch out of the dash with the power on and wiggle the wires. I pulled mine apart and re-crimped it and no problems since.

 

old thread, but im having similar issues.

with my 03 sierra, upon engine start, the truck will be in either 4 low, 4 high, auto 4x or neutral. it was doing this months ago, but just went away. now its back. i have a predator sport hand held, i should be able to scan for codes. until then, any ideas ? not lifted, not modified other than intake and my hand held "tuner".

 

Just came across this thread and wanted to give a little tip for future usres. If you have a service 4x4 light on your dash it is typically your push button 4x4 located on your dash. What happens is there are a few contacts that have cracked solder. It is very simple to fix. Just remove the buttons and look for the cracked solder and resolder it. No need for additional solder just heat up the old stuff. I forget the sequence of the fix but it's pretty easy. Better than spending 80 bucks or so.