4x4 not working fuse is good , took motor off its good , turn switch on dash nothing , crank truck 4low light comes on for about 3 second . Transfer case will turn manual by hand.got power to firewall vac switch'.
That only leaves a failed dash switch - OR - vacuum leak from vacuum switch out to front hubs..
Think about it - encoder motor is good - transfer case turns by hand..
I’d have a serious look at ALL vacuum circuits ... Smoke machine is only way to go for testing!
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Front hubs are the most problematic components for vacuum leaks.. You WILL need a smoke vapor machine! Good luck!