I have searched but cant find answer to my problem. 95 blazer front axle wont engage. Repaired vacuum lines and replaced vacuum switch. I can get it to engage if I jump the vacuum lines at the switch. What makes the switch work. I had the old switch connected and hanging with truck running and in gear and 4wd push the ball in axle engages so all the lines are correct and actuator and cable are good.

 

These vacuum systems are never ending problems!! I always recommend doing a posi lock setup so you don't have to worry about it anymore. It may or may not be an option for you but its cheap and works every time. I think its the fittest couple pages of my build thread of you want to check it out.

 

thanks for your help. found there is a linkage inside the transfer case that pushes on the ball on the vacuum switch to make it work. it is not really serviceable without a transfer case rebuild. will go with a later model vacuum switch mounted on the firewall and a toggle switch to activate it.