How to test the 4x4 actuator?

[Joel Hodgkinson]

Hey guys, 2007.5 gmc sierra SLT 4auto 5.3L mp3023

 

Ive recently replaced my transfer case as it was cracked. me thinking 4x4 would work after that was replaced. nope. brand new shift motor and sensors that attach to the transfer case. i took the 4x4 actuator out of the front diff and had somebody try and switch it to 4x4 and didn't see the actuator move at all. i stuck my finger in the front diff and pushed the pin and spun the left front wheel and the front driveshaft spun then.

 

my question is, im wanting to narrow it down to see if its just the 4x4 actuator or wiring. its a 4 wire connector that goes to the actuator. i hear the transfer case shift motor shifting when i turn it to 4auto/4hi/4lo but it just flashes 3x and goes back to 2wd and says service 4x4. What fuses would i check? whats power and whats ground on that connector? a wiring diagram would help a TON!

 

any and all info would be greatly appreciated! thanks.

 

 

Oh and ive also replaced front left and rear right wheel speed sensors as they were torn. i kinda bought this truck somewhat beatup.