My Blazer shifts from 2wd to 4lo no problem, but I can't get it into4 hi..

WTF?!?

 

The more info you give, the easier it is to answer.
I'm guessing that you have a 2000 blazer with a 2 speed selectable transfer case NVG233.
It sounds like you either have a bad electrical connection to the encoder motor or a failed encoder motor.

 

Same thing happened to my wifes 95 blazer. 4 hi no work, 4lo was good. I switched the switch in the dash and its all better. nice easy fix for me anyway.

 

Do you have the 4button autotrac 4x4 switch?

 

I do have a 2000 LS...

I have 3 buttons on my dash (2wd, 4hi and 4lo)... When I push the 4hi (when its in 2wd) BOTHthe 4hi and 4 lo blink... then switches to 2wd... When I push the 4lo button both 4hi and 4lo blink again, but it switched to 4 lo. And i feel the lower gears - so I know i'm in 4lo...

WEIRD!

 

Had a similar issue. Only I have the Four button Auto 4hi. On mine the low range would ingage in the T-case but not the front diff., so 4hi wouldn't work at all. Turned out to be that the cable from the vacuum actuator to the front diff. had frozen up. A little over $50 later and a new cable it worked just fine. The actuator is located under the battery on the inside fender. How to from sevrice manual below.
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