Maybe cable has a sticky spot? 3/4" seems about right.

They sell this kit to do it manually but I never found a Clean spot to put it.


4x4 Posi-Lok Positive Axle Engagement System for Chevy/GMC S-Series 4x4s

 

I have a 01 blazer 4x4 and wh en I hit 4lo, 4hi, i hear it clicking and thumping and sounds like it's shifted but the lights contue to blink. 4lo drives like it's in lo but not sure. The 2 light doesn't come back on automaticlly so is it locked into 4x4?

 

rntbuck Could you keep us posted on how this turns out. I'm having the same problem with my 97 Blazer. I can't seem to pull the cable out very far either. It won't engage the front axle. The acuator works fine, and holds vacum. All lights work and I hear a clicking sound when pushing the 4 wheel drive buttons. I unhooked the cable from the axle, and it appears to be working fine, no binding up nothing broken.

One thing that I did today, out of curiosity, was unplugging the TCCM to see if it might be the problem. I started the car back up, and nothing was different. Everything was exactly the same with it unplugged.

Could that be what's wrong?

 

I was wrong about the location of the TCCM. It turns out that it is the air bag module behind the passenger kick panel. That would explain why it didn't change anything...lol

From what I've read, the TCCM is behind the ashtray. I will go digging around and try to locate it.