A little further diagnostc info. Will not engage when going over 10MPH. I hitht e swthch, hear the transfer case engage and then a grinding noise starts.
Under 10MPH in neutral or reverse, 4 wheel engages just fine with no issues.
No light's blinking no 4x4 code thrown.
This leads me to believe that there just might be a small vacuum leak somewhere. It might not have the power to engage the coupler at higher speeds, but lower speeds it can slide over.
What do you guys think?