Fourwheel drive not working on 94 Yukon?!?!

[OffRoader93]

The fourwheel drive is not working on my 94 GMC Yukon. The transfer case is engaging and spinning the driveshafts fine. The electrical deal that locks the front diff is working, and I also tried to engage the diff by taking off the electrical device and doing it with an extension. It doesn't seem to lock in. Is there something that is common to break in the differential of these vehicles? I am lost? Any help would be great. Thanks.

Brenton

 

[RAY]

someone correct me if I am wrong, but your year used a thermal actuator. Basically, a heating element would heat the gas contained in it to expand the gas and slide ring and pinion together. It is pretty common for these to fail, especially in cold weather. Later models went with an electric motor which would probably work or you can buy a conversion kit that allows you to manually shift into 4WD. Hope this helps.

Ray

 

[OffRoader93]

Thanks. I have already taken the thermal actuator off and tried engaging it with a socket extension. The actuator works, but something inside is screwy. Any other suggestions would be helpful. Thanks.

Brenton

 

[84K5BD]

Possible the shift frork that slides the gear into place is out of whack.

 

[88sub4x4]

So when you manually slide the fork over and turn the front driveshaft by hand, neither of the front wheels spin? If something were broken in there yuo would most likely get a grinding noise. BTW, the ring and pinion are always in place, and the actuator just slides a collar over to connect the right side axle shaft to the right side stub shaft. Sorry if I just confused you.