Hello. I have a '95 Blazer, 215k miles with the NP1 233 transfer case, which has recently decided it wants to see how well i can drive in northern WI snow w/o 4wd. I will admit that i let her sit for the better part of 7 months (summer), but everything worked fine before that. I've searched a ton the past 4 days and here's what i've done...

1) Jacked up the front end, pushed 4hi and 4lo, spinning the front driveshaft by hand each time. The transfer case engages and stays in until i go back to 2wd.

2) Took out the battery and tray, lengthened the cables enough to reconnect the battery, and hit 4hi/4lo again. Transfer case is still good, but the actuator is not under vacuum. I tested the actuator for a leak with my vacuum pump and it does hold vacuum and pull on the cable.

3) Pulled the TCCM from the front kick panel and looked for corrosion. None there, and plugged in tight.

So can i safely presume that because of (1), my t-case shift motor is still good, and (2) that i most likely have a bad vacuum line or transfer case switch?

I plan on backtracking as many vacuum lines as i can that are associated with the actuator, but if anyone has a diagram of how they are run from the firewall back, that would be awesome.

Thanks.

 

i had to actually go on google to find it in the images for you but its from this site - i knew i remember ed seeing it on this site somewhere before but didn't see it due to a spelling error

https://blazerforum.com/forum/2nd-generation-s-series-1995-2005-tech-41/95-blazer-s10-vacumn-diagram-37998/

trace out your vacuum lines before you bother with anything else - that actuator needs vac to pull the cable & ur in a much easier to fix boat than i am with 4x4.

 

Yeah, well, that was easy. And it fixed my HVAC too (was only blowing from the dash vent). So after 3 layers of 'almost' the same problem, i find this thread : https://blazerforum.com/forum/showthread.php?t=7180.

About 3/4 the way down the first post was what i needed. It seems the vacuum line from the manifold has expanded slightly over the past 15 years and doesn't form a tight seal, so it falls off. 1 teeny-tiny metal clamp and i had vacuum. I lifted the front end with 4hi engaged and the wheels are locked together (although still in an open-diff kinda way /sigh).

Thank you.