4WD high and low problems

My 89 cherokee has got 4 wheel high and 4 wheel low, the 4 wheel low works perfect, but for some reason the 4 wheel high doesn't, we made sure it wasn't me just bein stupid and jacked all four wheels up off the ground and the front wheels would only spin in low. i have no idea why this would be. On a side note, does anyone know how to reset the emiss maint lights countdown timer?

My 89 cherokee has got 4 wheel high and 4 wheel low, the 4 wheel low works perfect, but for some reason the 4 wheel high doesn't, we made sure it wasn't me just bein stupid and jacked all four wheels up off the ground and the front wheels would only spin in low. i have no idea why this would be. On a side note, does anyone know how to reset the emiss maint lights countdown timer?

Is it Selec Trac or Command Trac? ...anyway....it is probably the vacuum system or hose connections.

There is a recent post to some service manuals that may apply to your year.

Try this link:

http://www.lunghd.com/Downloads_and_Links/Downloads.htm

If you are gonna fix Cherokees (XJs) you need these.