I have a 99 ls blazer with the 3 button 4x4 switch. when i bought it 4x4 did not work. I replaced the vaccumm actuator under the battery, and the transfer case switch. After this 4x4 did work in all ranges. This only lasted for one day. I tried one little mud puddle and then it went out again. I heard some grinding up front and it sounded like either the front axles are not engaging or maybe the shift fork is not engaging the connector sieeve. I had someone watch me pull away in 4 low on wet grass and the front tires did not pull. only the grinding and slipping noise. IM pretty sure that the problem is in the Diff. somewhere but i dont know where? How hard is it to drop the diff and would it be worth it to have the problem diagnosed at a shop? Could my axle shafts be stripped? Any help would be appreciated.

THANKS FOR THE HELP

 

ANY HELP?

 

#7 - frozen or tight. Lubricate and work back and forth until it is nice and smooth. Verify that this is the problem by manually pulling on the cable at the actuator and locking it in place with a vice grip. This problem has been covered many times.

And please give us some time to reply. No need post again barely 3 minutes after the initial post with a picture that has been posted in numerous other threads...

 

Thanks ill give it a try. I hate this 4x4 system.

 

SO i took out the cable it moved fine but i oiled it any way. I made sure that the pin was getting pulled and it was. I noticed that there was a little diff fluid leaking out around where the cable attaches to the diff. I put it back together left the battery out and jumped it. it started and i put in in 4hi the actuator pulled in and the cable moved and pulled the pin. But when i took it for a drive no 4x4 just a clicking noise from the diff. Also i have read that the driver side tire should spin even if the passenger tire is not engaged. I dont know what else to look at. Could the shift fork have broken? or do you think its more serious like a blown ring and pinion gear.
Thanks for the help

 

Not sure where you read that the driver side tire would spin even if the passenger axle was disconnected. With the open differential, if on side has no traction, it will receive all of the power.

So if the cable is pulling all of the way, but it still is not engaging inside the diff, sounds like you have to drop the passenger side axle tube and inspect inside.

Have a look at the link below:
Not Just Another Inop 4X4 Problem

And here is what you will see inside the front axle housing:

*Image found on ZR2usa.com*

 

Ill give it a try and take pics thanks.