It goes into 4lo but front doesnt pull...I need help.

[Jason_25]

Maybe a front diff vacuum leak??

Maybe the reason the rpm's drop and the voltage drops is because when the solenoid opens up the vacuum for the front end it creates a leak, and thus a rough idle.

2 questions:
1.Do you wheel the truck hard?
2.When you put it into 4-low do you feel the "clunk" of it going into 4-low?

 

[yob_yeknom]

Whoa... hold up.
Front axle should not be the problem since it turns in 2wd. I believe it is the t-case clutch.

Further testing: lift your entire vehicle on jack stands. Have all wheels off the ground. Put it in 4low and see if the front driveshaft turns.