I have a 2000 zr2 blazer.
We more or less think we have the t-case itself being the actual problem but I figured I would see what everyone else suggested. Because I have heard there can be lots of things to look at that could be wrong.

First off the 4x4 will not work at all. We checked the vaccum lines. There all good.
Checked the vaccum...good
The front axle spins when the 4hi is engaged
The driveshaft will not turn even in 2wd. The motor is engaging and you can hear it shifting. The vaccum ball under the battery is engaging (moving)

When selecting a 4x4 option im pretty sure there is was a clicking sound and a blinking light.
We have come to the conclusion that the tcase needs to be replaced even after we replaced the expense oil for it also....
With it being a 4 button switch with the auto 4x4 im pretty sure I will need the nv236 tcase.

I didn't think it would be so difficult to get this working correctly with all the different scenario.
I have heard that the 2000 zr2 blazer is a stand alone year for the t-cases. Is this true?

Anyone with knowledge of this issues, I would gladly like some input to make sure we went through everything that It could be before dumping money on things I don't need.... Thanks

 

Before you pull the case take it to someone with a capable scanner and have them see if there are any 4X4 codes. They will not show on the cheap scanners that autozone and most of us have.
Rather it be the TCCM for $50 on ebay then the entire case.

 

i believe you can check for codes yourself by jumping pin 13 on the data link cable (under dash) to a ground (pin 4-5) the selector switch should display codes if there are any. at least on my 233 t-case not sure if its the same on the auto 236 im currently troubleshooting my 4x4 on 2000 blazer as well

 

I believe the 236 case (four-button) doesn't display codes the same way the 233 (three-button) case does. I seem to recall that someone had posted an answer to that question before here on the Forum. A good search may turn up a definitive answer.

 

sorry my mistake-just trying to help