My dad's '99 has the front drive shaft always turning. Checked the transfer it is in two wheel drive. When stopped the you can't turn the front drive shaft, that is telling me that the coupler is engaged. How do you trouble shoot the vacum switch or the actuator on the front axel? We have already replaced the transfer case.

 

I was under the impression that with the CAD system one side of the axle is always connected to the driveshaft. Then when the coupler is engaged both axleshafts are connected and the transfer case engages the front driveshaft. In this situation you would not be able to turn the driveshaft because one tire is connected all the time. If you could turn the driveshaft the entire truck would move. It isn't, however, powered by the transfer case until the lever is moved.<br><br>Can you lift the front and try to spin one or both tires? If the above is true then one will spin freely and the when the other is spun the driveshaft will also spin. When the coupler is engaged both tires will spin.<br><br>Sorry if this information is wrong. I have a non-CAD 2002.

 

My truck is a '99 and the drive shaft spins free until the transfer is engaged.<br>

 

I'm not 100% sure but it pretty sure mine will spin by hand until the transfer case is lockd in.
Aaron

 

The '01 and previous trucks have a disconnect in the front axle. The drive shaft should spin freely by hand when in 2WD. However, in 2002 they decided to save money and put in a &quot;live all the time&quot; front axle. My '02 front shaft turns all the time. The '99 should be disconnecting in 2WD. Sounds like a problem.