2002 2500HD vacuum leak 4x4 actuator

[tate330]

I have an ’02 2500HD 8.1L W/ allison transmision. I am wondering where to start looking for a vacuum leak around front axle?

 

[Molson02536]

I have an ’02 2500HD 8.1L W/ allison transmision. I am wondering where to start looking for a vacuum leak around front axle?

Full size pu trucks like yours don't have a vacuum front axle actuator, it's all electrical. Start with checking the fuses and the wire harness to the front axle actuator.

Good luck and keep us posted from there, and since you have a 02 it will have the new electrical actuator which is not thermal activated like the older ones.