My 2002 Blazer has lost its 4 wheel drive. I have all vacuum, a new transfer case switch, I have drive to the front differential, I can hear the transfer case switching and the drive shaft is turning. While on jack stands, with transfer case switch removed but still connected to vacuum lines and manually pushing plunger, the front differential locks in. But when all together, it won't work. Any ideas??????

Can a transfer case motor on a 2002 Blazer be good enough to engage drive to front differential but not good enough to activate the transfer case switch?

 

*Combining posts on the same topic* Lets keep this all together since they both deal with your front axle engagement.

If the encoder is shifting the transfer case into 4HI and 4LO, then it (the encoder) is doing what it is supposed to be doing. On the other hand, if the shift sector (55 in the diagram attached) is bent and not properly contacting the plunger on the switch... That's a pretty out there occurrence though.

Are you sure you have the proper switch for your application?

diagram courtesy of drivetrain.com