Service 4 WD
 

Service 4 WD came on my message board and was wondering why?

there is a fault in the 4wd system. post make, model, year, engine and the code set in the tranfercase control module...full function scan tool required...code reader cannot access chassis codes.

A few more questions. Do you have a knob on the dash to control the 4WD and if so does it have a setting called “ Auto “. Lastly, how many miles since you changed the fluid in the transfer case.

SD

Make, Model & Year
 

It is a 2002 Chevy Avalanche 1500

Just had my transmission rebuilt about a month and half ago

Yes there is knobs on the left side of the dash to control the 4 W D. and yes there is one that says Auto

I guess the follow up ? is, is the led on?

The transmission is separate from the transfer case. The transfer case fluid needs to be changed every 50,000 miles.
The fact it’s an auto transfer case makes this even more important because there are clutches inside the case that rely on the fluid being in good condition.

Service 4 W D
 

Ok Thank you very much! Now the message on the message board is gone but it also came back on and off a different time, I read that there may be a glitch with a sensor on the transfer case.

The (that) transfer case has clutch packs, and an electric shift motor. Always important to service everything. These images are a transfer case, shift motor (probably your issue), and clutch disk that was removed, and disgarded. Son's 2000 took a transfer case, replaced input bearing, drilled, screwed the clutch disk together so as to get rid of the shift motor. Engages the front differential when he needs 4wd.

https://cimg9.ibsrv.net/gimg/chevrol...084176773a.jpg

https://cimg0.ibsrv.net/gimg/chevrol...04a18fe1b7.jpg

https://cimg5.ibsrv.net/gimg/chevrol...7a6498df31.jpg