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GM AWD issues?

Lifted 1 front wheel off ground and idled in drive to check wheel bearing. I could hear a rhythmic on/off pulsing sound from rear of vehicle? I looked under and see driveshaft is turning and the noise is coming from rear diff area? Center carrier bearing also bad as driveshaft has visible play. So, trans is in drive and front tire is moving so suv thinks it is “moving” and slipping so power is being sent to rear? And driveshaft turns with both rear wheels on ground? What is allowing freewheeling in rear diff with both tires locked?

There is a clutch on the front of the rear differential that allows slippage, it should engage when there is front wheel spin. If you push the accelerator maybe you could drive the vehicle off the jack stand and though the garage wall.


Umm, yeah, first thing I thought when I read this is “Are you crazy?”.

3 wheels on the ground and idling in drive? Don’t do that.

Cavell , do you run a used car lot ? If so why not hire a real mechanic before you injure yourself.

Guess I had a brain freeze. Awd and spinning 1 wheel? No, everything I do is for my amusement. I did find an exploded view of rear diff. There is a side-to-side clutch setup but I was not aware of the driveshaft input clutch. Is the power from front transaxle always being sent to rear and the rear clutch controls the input?

Model year?

The black box on right side is clutch apply module. It’s an 06. Seems most of the gm small suv’s share similar design. There is a clutch drum assy that causes issues. Many folks complain of vibration from failed carrier bearing on moderate acceleration so I assume driveshaft is turning in most cases.image