My 96 Blazer is having some 4wd issues right now. I have the 3 button switch on my dash. I don't think it is the button on the dash since I can hear the transfer case engaging & I can see the front drive shaft spinning in 4hi mode. However when I put my truck on a lift the other day. The 4x4 is not working. I proceeded to get under the battery tray. I noticed when the truck is even in 2wd. The actuator sucks itself in when I turn the truck on. I'm not sure if it's supposed to engage itself in 2wd?? I replaced the actuator under the battery tray & the actuator cable that goes to the front dif. I even swapped out a TCCM from my friends Blazer that worked just to see if that was it. Still doesn't work. I looked all over this forum, but I don't see any post about the actuator engaging when the truck is even in 2wd mode. It still stays engaged when I put it in 4x4 though.

 

This is the same problem I have with my 96. I ordered a "transfer case vacuum switch". Hopefully this fixes the problem. I will let you know if that helped or not. I have the same issue with my actuator always being compressed in when the engine turns on.

 

That's the problem, the spring loaded ball in the switch gets stuck and keeps vacuum applied to the actuator. Cheap fix, Dorman part #600-500 and takes about 15 minutes to replace it.

 

It was the transfer case vacuum switch. Thanks for the replies! Now this may seem like a really dumb question, but when I had all 4 tires up off the ground. My 4wd was working, but when I got out to look. My drivers side tire was spinning without giving it gas. My passenger side tire was no spinning unless I gave it some gas, but it seemed like it didn't want to budge too much. Is this normal on a stock blazer?

 

Normal operation of the front differential. If you keep the left front from turning, the differential will power the right front wheel. The same holds true with the rears.