94 tracker transfer case

My 94 tracker is not shifting into 4h while moving faster than 5mph. Yesterday it shifted fine, the next day it grinds and will not engage unless I stop or slow to 5mph. Any ideas?

almost all trucks need to be shifted in a stop mode to any 4x4 function, how you did it must of bin a fluk.

almost all trucks need to be shifted in a stop mode to any 4x4 function, how you did it must of bin a fluk.

I disagree. The manual states that you can engage the transfer case into 4H from 2H while driving at highway speeds, although I usually do so around 20-30 mph. My Toyota and Ford also can be engaged while driving. The Tracker has shifted fine while driving for years, it just stopped the other day. I suspect a sync problem.

I disagree. The manual states that you can engage the transfer case into 4H from 2H while driving at highway speeds, although I usually do so around 20-30 mph. My Toyota and Ford also can be engaged while driving. The Tracker has shifted fine while driving for years, it just stopped the other day. I suspect a sync problem.
I suspect your synchros bit the dust.