Does anyone know of a reason why I would only have 4WD in high range and not in low. Everything else is working fine except 4WD low.

 

The first thing that pops to mind is the gear position sensor. When this sensor 'thinks' you are in reverse, it cuts power to the 4wd. Could be out of adjustment somehow.
Does you 4wd work when you hold the override button? If so, I would think it is in the sensor.

 

The 4wd works in reverse when I hold the button but not when I am in low and hold the button.