The grease in the low/Hi stepper motor can also turn to an almost solid mass which causes it seize, mostly due to lack of use.
Taking it apart and giving it a good service / clean out usually works wonders, it is so rarely used..
Also Between the transfer case ECU and the transfer case shift motor there is a connection in the wiring loom it is buried under the centre console almost directly under the box behind the window switches), where the SRS ECU is located worth checking under there at the connectors as there can be a problem there.
Up to MY 1999 there are 3 connectors there - 2 way Black power to the ratio motor, 10 way White which is the connection between the gearbox and the ECU, and 20 way Black which has the ratio motor position switch wires in it among other things including other gearbox connections
Might be worth having a look there if you have any problems.
Also worth trying to reset the ecu
Turn the key to position 1.
2. Press the throttle pedal to the floor and hold for five seconds.
3. Turn the key to the off position don't remove the key, then release the throttle pedal.
4. Wait at least two minutes for ECU to reset.
5. This will clear the Potentiometer settings and typically allow you to go into low range. If this works, then you need to go between low and high range 3 times. The first is from a dead stop and the second two are while moving around 5-10 miles an hour (you still need to shift into neutral and drive which moving.
H