2003 GMC 4WD Question
 

I just replaced the transfer case due to the pump rub problem. Got everything in and running fine for couple of weeks now. This morning the check 4wd light is on and none of the indicator lites (2hi,4hi,4lo,auto4wd)are on. Drives fine though Any ideas??

Re: 2003 GMC 4WD Question
 

Have you scanned it? I'd start there.

Re: 2003 GMC 4WD Question
 

Chances are the previous issue and the latest service 4wd is not related. GM’s electric shift 4wd system is pretty famous for dropping Service 4wd lights. The system is just too complicated to do the job of what a simple lever used to do before people that should be driving cars started driving trucks resulting in all the manufactures making electric shift the norm instead of the exception. This isn’t just a GM issue…. Dodge, Ford, Toyota and the rest have the same issues.

In GM’s case, chances are the control head failed (button assembly on the dash) but transfercase control module failures (TCCM) and encoder motor (motor on side of tcase that is constantly gets soaked with dirt and road salt) or any of the 12 lbs of wiring that support the system has chaffed on something due to GM's piss poor wiring harness routing are all very common failure modes as well.

As Benelli stated, pull the codes and see where that leads you. You will probably find the control head switch died, which is the cheapest part…luckily. The TCCM is the pricy piece and more common to fail on TrailBlazer’s and Envoy’s but GMT800 trucks are not excluded.

I have 3 GMT800 rigs. 2 of which have levers on the floor for these reasons. I had to settle with the electric shift crap on the 3rd because it was standard on SUVs after 2000 model year.

Re: 2003 GMC 4WD Question
 

Thanks for the replys, seems to be the dash swich.