Drivetrain thumping with AWD (ATC Fuse) On

[DMT00]

When the ATC fuse is in, thumping coming from somewhere under the van, hard to pin point. This seems to go away after second gear, but it could still be there but muffled by the higher speeds. When I pull the fuse this all goes away. I plan to do some investigating once its light out again. Just got it legal tonight. Any ideas? Is this a common symptom of a tc in need of some help?

Thanks.

[MountainManJoe]

Hello and welcome.

You should at least give us the year of your vehicle, but I'll wager a guess and say it's '99 up. If so, then I'll also bet you're experiencing the all-too-common transfer case clutch slip-stick problem. Kinda hops when you gently accelerate around a sharp turn at around 5mph right?

The solution is to drain and fill your transfer case will GM's improved Autotrak II fluid. It costs around $5/quart.

Let us know how it goes, and hopefully see you around.

[DMT00]

Yes you are correct. It is a 2000. I apologize for my lack of information in my post. Thank you very much for the info. I will pick that up soon and throw it in.