4wd not working

[daveid]

I have a 95 gmc sierra and the front wheels dont turn when I have it in 4wd. I looked down at the driveshaft and its just spinning even when the brakes are on? Are the gears maybe stripped?


thanx
david

[curtis73]

a common problem was the electric servo motor that engages the transfer case. That would be where I would check first. If the gears were stripped you would have heard horriffic grinding and it would have been a long-time progressive problem.

[daveid]

THANKS!! Do you have a quick way to be able to check it or how to check it? IVe never delt with 4wd nor much of chasis work.

thanx

[curtis73]

Honestly no. I always opted for the manual transfer case cause I'm too cheap

If the driveshaft were spinning as you drove, but no power was getting to the front wheels, I would suspect the hubs, but since you said you can just spin the driveshaft, that means the transfer case is not going into 4wd.

[daveid]

sorry, i explained wrong. it is spinning while driving and not driving. its not spinning by hand or anything. but once its in 4wd then the front drive shaft just keeps spinning.

thanx again

[curtis73]

Ah... OK, then its probably the hub engagement servo. Its another common issue. When they went to the automatic hubs there were problems with the servo that engaged them.

[daveid]

is that what is also reffered to as a actuator? Thanx for all the help. this isnt the first time youve helped me and i appreciate it

david

[curtis73]

Yup. I think the parts book calls it "servo; actuator, front axle"

[daveid]

Thanx. that was exactly it. Glad it was so easy to find and replace.

thanx again