99 blazer 4x4 problem

I have a 99 blazer 4x4 with push button controls..when I push 4 lo it sounds like the transfer case locks in but the light just flashes and the frontend doesnt lock in...I used to be able to rock the truck front to back and get it to lock in but now it wont

I have a 99 blazer 4x4 with push button controls..when I push 4 lo it sounds like the transfer case locks in but the light just flashes and the frontend doesnt lock in...I used to be able to rock the truck front to back and get it to lock in but now it wont

What transfer case does it have?
Auto 4W or reg?
How many shift buttons and what do they say on them?
Doe all 4W high shifting stuff work good?

Have you checked for transfer case codes?

Does front drive shaft lock in in 4W high and 4W low positions?

Thanx MT but as soon as I posted this I found the thread u posted on this problem..you explained how these systems work and it helped me track down the problem...a leak in the vacuum line..thanx again

I have always built my own 4x4 trucks so I am pretty good at fixing them..but this is the first truck I have owned with this push button set up so I was a little lost on how it all worked....your the man

You are welcome and glad you got it figures out.
Like everything else they are computer controlled.
Good Luck