I have an 07 Yukon 5.3 and when it gets cold out(-10 degrees and colder) my service 4wd light comes on and the 4wd doesn't work. Once the vehicle starts to get warm it will work and the light goes out. I forget the number for the code but I'll scan it in the next hour or so and post it but the code was "transfer case module unresponsive" or something to that measure. Anybody have any ideas? Other than a poor connection or an intermittent open somewhere.

 

could be an actuator problem

https://chevroletforum.com/forum/tah...problem-62517/

 

The code is U0102 "lost communication with transfer case control module" it only comes on when it's colder than 10 below zero and goes away when the vehicle warms up but comes back on after it cools down.

 

Could be a connector or bad ground.

 

Change the Fluid.
AutoTrak ll, 2qts.
Once you do and get it warmed up and working, repeat the 4hi to 4lo change several times in succession.

 

depends on which t-case he has.