I have been working on a 93 blazer 4wd system and it goes into 4high but jumps out into nuetral in the t-case but 4low works fine. It has a pushbutton 4wd and all the lights work and you can hear the motor engage and all sounds fine. Any help would be appreciated.

1 of 4 things... Encoder motor is bad...(too weak to fully engage), Vaccum switch on side of transfer case. You're low on the transfer case fluid.... Or a worn out transfer case...

Start in that order...