Underhood Vacuum lines 3-button, NVG233 transfer case (RPO NP1)
 

Below is what I have been able to glean from several sources with regard to the underhood vacuum line routing for the second gen Blazers with a 3-button transfer case. Since I do not own one of these, I cannot be sure of the sizes of the hoses. Instead I used the parts numbers and descriptions from the webpage from which I got the exploded parts diagram.

For the connections to the vacuum switch on the transfer case that allows vacuum to be applied to the front axle cable actuator, I used several posts from other forums. I could not find a definitive source for these hose connections to the switch. In the diagram there is a discrepancy between the hose routing and the color-coding on the switch itself. I would lean toward the color coding on the switch itself being correct.

If anyone sees any errors, please let me know and I hope this is some help to people.

Christine

Links:
https://nemigaparts.com/cat_spares/e...t/06/ts06-502/ (main exploded parts diagram that was the basis for the final diagram)
https://nemigaparts.com/cat_spares/e...t/06/ts06-503/ (exploded parts diagram for 1st gen Blazers)
https://chevrolet.7zap.com/en/europe...94&node=144448 (for vacuum reservoir location)

Other Useful Links:
https://blog.1aauto.com/2nd-gen-chev...mmon-problems/
https://www.s10forum.com/threads/4wd...10-2-8.873999/
https://www.s10forum.com/threads/the...327817/page-28
https://blazerforum.com/forum/2nd-ge...s-40178/page3/
https://www.s-10crewcab.net/og1/modi.../tcswitch.html
https://cimg8.ibsrv.net/gimg/blazerf...d313fd4acd.png