Service 4wd no lights on the buttons - 2004 Chevrolet Avalanche

Check the vacuum switch under the hood in the center of the firewall...follow vac diag

There are actuators on the front axle and the transfer case, check them both.

Light on , DTC- diagnostic trouble code stored in the 4X4 control module . Take's a professional type scan tool to read these code's . Your best bet AAMCO . or dealer .

sounds like you have a wiring problem in the 4WD. Probably the servo motor id disengaging once it gets hot. If you plan on fixing it yourself I\'d go buy the service manual. Wiring issues are so annoying.

if the 4wd switch doesn't light up to show what mode it is in the tccm will set a code and the 4wd light will be on the fuse is in the under hood fuse block I forget what it is labeled as

Well it could be the selector switch, but I doubt it.
Generally, the service light means something is not working that the computer controls. Solenoids and valves are a couple of possibilities.
The transfer case is shifted by solenoids commanded by the body computer based on the switch position on the dash.
You should be able to have a shop scan the body computer for trouble codes and proceed from there.
A basic code reader may not access the body computer.

At www.reliable-store.com get complete guide on whether to repair or not, service it, and how to repair etc, along with wiring diagrams, electrical diagrams, torque specs, error codes, everything.

Does the 4-wheel drive work ? Most of the time, it is a reminder to have your fluid changed. Other times, it could be a vacuum leak in the line that engages the 4-wheel drive. Check both of those first.

Behind the kick panel on the passenger side is an electronic box. unplug the wiring harness and inspect for corrosion, clean and reconnect.

service it like you would the truck engine it will have to be reset by the book almost like the truck i had that same problem