4 high and low won't work. But 4 auto will.

[Tman1295]

I have an 04 Silverado 2500 6.0 and the 4x4 won't work. Have a brand new transfer case, and replaced the axle actuator. 4 high and low still won't work but the 4 auto works. Is there a special way that it needs to be out into 4 high? I know how to put 4 low in. Can low transfer case fluid cause it not to work? Kinda stumped here.

[00Silverado4x4]

You said you replaced the axle actuator but the encoder motor on the transfer case may be messed up as well. I'd get it scanned for codes and then go from there.