2002 4WD Issue.

Hey guys I need some help....
2002 Envoy XL 111k
When I start the truck the light blinks on the selector for the 4wd. But after i drive it, it goes back to normal. The 4wd does not work. I narrowed it down to the front drive axle actuator through talking to a local GM tech only because before I for the truck from my dad he had a complete over haul on the transfer case. Plus I also hear the transfer case sliding when I turn the switch.Any other ideas....

Majordiezel said:

Hey guys I need some help....
2002 Envoy XL 111k
When I start the truck the light blinks on the selector for the 4wd. But after i drive it, it goes back to normal. The 4wd does not work. I narrowed it down to the front drive axle actuator through talking to a local GM tech only because before I for the truck from my dad he had a complete over haul on the transfer case. Plus I also hear the transfer case sliding when I turn the switch.Any other ideas....

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The front axle actuator has an internal position feedback sensor that makes sure the button goes all the way out. If it fails to succeed, the TCCM knows it, and turns on the Service 4WD light and then quits trying to run the actuator.

The other issue would be a something bent or worn inside your spline disconnect assembly. I really think it's more likely that you have a worn spline collar, where the normal engagement distance that the actuator pushes it in just isn't enough anymore. When you push it manually, it goes in farther and gets into some working splines.

The actuator's position feedback sensor (the copper stripe with the gap in it) is presumably designed to change state after the actuator is pushed out far enough to operate. I've seen pics of worn splines on the intermediate shaft that might have engaged with a farther collar push.

You'd save money if you buy one from the Salvage Yard and replace the old actuator instead of buying a new actuator first.

Keep us posted and hope it's just the actuator.

ok, so i have not been able to get to the lift at my buddys shop so i have been forced to just do it on my back, but unfortunatley with all the snow up here in Ny i havent been able to try anything. So today while i was out there i had picked up the front end of the truck and had my father cycle the 4wd selector and i can feel the front drive axle actuator moving. You can also hear it moving with the key on and engine off. My friend is telling me thats its defff something internally and something i most likely will have to either bring to a dealer or tranny shop?
Thoughts?