[jlberg3]

I own a 94 GMC Jimmy 4x4, I have had the problem before of no 4Hi but the 4Lo works just fine. my issue was fixed by replacing the transfer case electric shift motor located on the front of the transfer case. (It almost appears to be a little starter motor)it is held on by three bolts, and is right by the front drive shaft yoke. You must remove the front drive shaft to replace it. (on mine it was necessary to remove the front drive yoke to remove the switch) while you are down there you should check the vacuum switch. (it has three hoses connected to it) Pull the connecter with the hoses off . This connecter should be dry. if it has trans fluid in it replace it too. this vacuum switch is for your locking hubs. it is possible for your front shaft to be engaged and spinning without the front wheels getting any power to them.

[tnsmith10]

Originally Posted by ChevyJim

got a 95 gmc jimmy ( 4.3 , auto etc.) went to shift into 4 wd high today, and wouldn't shift. Got it home, played with the 4x4 buttons and found that it will shift straight from 2 hi to 4 lo, will not go to 4 hi. any ideas? indicator light not burnt out. drove it in 4 lo, then tried to go to 4 hi, it went straight back to 2 hi. I'm stumped. am I missing something stupid? should I trade it a brand spankin' new Amish buggy? lol. I'm ready to start running my 24 year old chevy truck again, its still more reliable than anything new I've had!!!
any help is VERY much appreciated.

this will either be a interanl t-case malfunction or an encoder motor problem.
you need to have it scanned for codes since its a full electronic. if the truck does not have a SES light on, then it will take a scan tool, not a code reader.