I Have A 94 Jimmy With Electronic Shift 4x4 Completely Inop. Unless Trans. Is In Neutral Once In Neutral Will Go In High And Low Lock But Intermittently Wont Disengage G.m. Flow Charts Are Useless Due To Improper Released Info. If Any One Can Shed Some Light On This It Would Be Most Appreciated Oh By The Way I Own Two Of These Trucks And Both Are Having Same Problem So Swaping Parts Back And Forth Probably Wont Help

Quick and easy check, make sure all 4 tires are the same manufacturer, same size, and all have the same tire pressure.

Thanks For The Reply But Not The Case Seems To Be Some Kind Of A Control Issue Has To Have Signal Missing From Some Were The Symptom Is There Moving Or Stopped

Is it the one with the rocker switch for 4W?
Will it shift back out of 4W when in neutral?
Does it shift into 4W low and back to 4W high good?
Is the front axel locking in?

Tell us what the shift lights are doing when it will not shift and when it does.

You can check for codes by jumping J and A or grounding pin J on your diagnostic connector.
If any codes post back codes.
MT

Thanks For The Reply, Yes The Front Axle Engages And Disengages When Finally Comes Out Of 4x4 Mode When Put Back In Neutral Will Come Out Of 4x4 After Screwing With It For A While When It Wont Both High And Low Range Lites Are Lit Up Troubl Code Charts On These Are Very Vague And Lead Back To Encoder I Know G.m. Mechs. Who Have A Hard Time With This System They Say Good Luck Most Of The Time Its Not The Encoder They Usually Replace Everything And Wash There Hands Of It I've Been A Mech. For Almost 20 Yrs And Have Had Problems In The Past With These And Now I Own Two Of These And Now Its On My Dime Cant Afford To Replace All Major Components

Check for any codes and post back codes if any.
Binding up in 4W can give problems shifting out of 4W
Also when shifting out or in 4 wheel try backing up a little and rolling forward.
And see if that helps.
There is a lot of things to spline up and unhook in and out of 4W.
As Old master says uneven worn even if they are a matched set tires can cause a bind up.

There is a vacuum switch on the transfer case with 3 vacuum lines connected to it. The switch controls the differential actuator. The switch can develop a leak and suck transfer case fluid into the lines, which slows down the action of the differential actuator. One of the lines should have manifold vacuum when the engine is running, one goes to the differential actuator, and one vents to atmosphere. Make sure they are not contaminated with transfer case fluid. If they are, keep a close eye on transmission fluid level. If the transmission rear seal leaks, it can leak transmission fluid into the transfer case causing the seal in the vacuum switch to deteriorate. Could also be a problem with the TCCM or encoder motor, but checking the vacuum lines is free.