I have a 2000 GMC Sierra with the auto 4 wheel drive. And I have been having a little trouble with it. It all started I believe this summer was putting my boat away. I was backing up a steep hill in 4 wheel drive and had the wheels turned at full lock. It was the only way to put the boat where it needed to be. This made the front end seem to bind a little because the wheels could not spin from all the weight. They say you need to only turn at full lock when the wheels will be able to spin slightly.

Now it seems like the auto hubs are sticking or heating up and sticking in 4 wheel drive mode. When I start driving everything is okay. After a few miles the light that indicates 2 wheel hi goes out and none of the lights show. I can press the button and have the 4 wheel auto light come on indicating it is in 4 wheel auto or the same for 4 wheel hi. The Service 4WD light came on once a few weeks ago for the same problem.

I have read the other posts that say it is most likely the switch that went bad. Problem is it feels like the 4WD (Wheel hop at full lock turn) is on when the 2W Hi light goes out so it doesnt seem to just be an electrical issue. Could it just be the switch is malfunctioning and causing it to go into 4WD. Also does it really help to run the truck in 4WD every once in a while to get the oil flowing?

Thanks for the help. Just trying to diagnoss the problem before I take it to the dealer and they charge me $1000 to put in a $70 switch or something.

No Help?

Could be that something electrical with a switch or even a fuse is bad and may be sending the wrong signals to the actuator. Or maybe even the actuator itself is bad. Also when you are in 4wd on pavement or stone your wheels should not spin, at all. To test if your 4wd is working, engauge it on a dirt road or stones and floor it, if it is working you should spin very little and if it isnt working you will definatly know. Not a good idea to put the truck in 4wd unless you plan on using it for something, ie: do not go down the road in 4wd as it will cause things to wear and eventually break. My best guess would be a relay switch or maybe even the actuator itself, but you should get it checked out.

It seems like the actuator is working correctly. I can hear it when I press the button. Some days I have no issues and some days I have the problem. I am beginning to think more and more it is the switch that is bad. I rarely drive my truck. Should I just replace the switch and see if that works or should I take it to the dealer to have them look at it? I try to avoid taking the truck into the dealer because it seems like every time I take it there it costs $500. Thanks for the help

Yeh do that first, im assuming the switches and or relays are rather cheap. and then if that doesnt work you should prolly take it in to the stealership.

I read on here the part is only $49 so I was thinking why not give it a try.