2000 gmc 1500 4x4 no lights and stuck in low range??

[braveops]

hey all inlaws 4x4 has the dreaded 4x4 problem 4x4 work when parked and been sitting for awhile battery went dead charged it then sat for some time.now fired it up and no lights on the push buttons only when you first turn key on then dissapear and was in nutraul.i picked up a new encoder and put it in now its in low? it had a switch put in about 300kms ago and when it was it had codes of c309 and b27725.i have cleaned grounds and pulled fuses and tried #13 to ground and it didnt blink on the switch? when i put atc fuse back in i can hear motor doing something.

service 4 wheel light on in dash

 

any idea what i can do. i dont have a tech 2

[braveops]

i got the c0309 code showing up. anyone know the correct way to test this? i cant seem to find out how to diagnose it

[gmtech4]

ya need service information to follow the code ,,,,,Alldata is $27/yr

 

ya dont need a tech 2 ,just a scanner that does more than read codes ,,,or it goes to a shop ,,,,,simple