[deanp]

We have a 2003 Chevrolet Suburban that has AWD and the Stabilitrak system and 175k miles.

We get the occasional traction control warning when leaving stop signs, etc, turning traction control off makes that go away. Suspected wheel speed sensor that needs to be changed.

It developed a shake under power, doesn't happen when it is first started but after 10-15 miles. Felt like a CV joint or U joint.

It has the Borg-Warner 44-82 AWD Transfer case. Fluid is within 1/8in of full at the fill hole, fluid is clean.

It is currently on jack stands with all four corners in the air. The transfer case is supposed to split power constantly at 40/60 f/r.

When I put it in drive or reverse the rear wheels turn, fronts don't. The front driveshaft isn't turning.

When I switch to 4LO it turns traction control off and operates normally, front and rear wheels turn.

I switched back to AWD, turned the traction control off, front wheels turned briefly, then stopped.

With the truck off and in neutral I can turn the rear driveshaft by hand and the front does not turn.

The front driveshaft feels a bit like it is binding when turning by hand, it freely as the rear.

Thought? Internal transfer case issue? Stabilitrak issue (no dash/message center warnings, etc)? Switch issue?

There is an actuator motor on the rear of the transfer case housing.

TIA