just took the wife out their to make sure the brake was all the way depressed an it still didn't move when switched into 4low..

 

Here are some of Possible Source(s):
4WD mode switch.
Neutral safety switch.
Brake pedal position (BPP) switch.
Transfer case mechanism.
Digital transmission range (TR) sensor.
Circuitry.

I will get back to you on how to test them. I have to figure out how to format the tests so I can post them.

JMC