have 2002 envoy and the service 4 wheel light is on, but after the car is warmed up and i restart it goes off, also i have pulled the fuses and put them back and :confused: had it reprogramed. and ideas??

Welcome to AF, needs to be scanned for 4wd issues for a proper diagnosis.

Loose connection / ground making contact when it warms up???

when i had someone look at it, i was told it needs a new transfer case control module. i just dont understand why the light goes off when it warms up. is that something the control module does?
thanks for any info

Yes it could but, without proper diagnostics that is an expensive guess, they were problematic though.

Get it computer diagnosed. Mine was the front, a LOT less expensive then the transfer case servo. And, yes, it does go on or off with time and temperature. The cheap plastic binds the shaft & it wont move enough to close the indicator contact - or wont move at all. Cycle the selector with the engine off and listen carefully for whirrs and clicks. There will be one click "missing" if one of actuators doesnt drive "home" properly. Takes two people, one to cycle the knob and one underneath to sort out where the whirrs and clicks are coming from.

thanks very much for your help
had my nephew look at it and he changed the chassis brain box and he got it at the junk yard for 100.00, the dealer wanted over 300.00 just for the part not labor. so i'am very glad i had a smart nephew.
everything works great now, and its a good thing with all the snow we have had.
thanks again