This is the pertinent part ...

If this truck was mine I would:

1. Shift into 4WD and move truck a couple of feet
2. If light is still off, park truck, block the wheels, set the park brake, jack right front wheel, and try to hand spin the wheel
   • If wheel doesn't turn, 4x4 is functioning properly but there is a wiring problem: use an ohmmeter to check the 4x4 switch, wiring, fuse, and bulb.
   • If wheel turns freely, the front axle or transfer case is not engaged: continue...
3. Attempt to hand spin the front driveshaft If the driveshaft WILL spin, the transfer case is not engaged Check the transfer case shift linkage, problem is in linkage (or in the tran$fer ca$e internal$ <-- yes this means $$, ouch!)
   • If the driveshaft will NOT spin, the transfer case is engaged properly: continue...
4. USE CAUTION! With transmission in neutral or park, start engine, measure vacuum on the two vac lines at front axle shift motor. One line should have approx 20" vacuum, other line should have none.
   • If NO vacuum measured, look for vacuum leak or bad vacuum switch.
   • If both lines have vacuum, look for a bad vacuum switch or ruptured CAD actuator diaphragm.
   • If one line has 20" +/- vacuum:
     • Move transfer case lever to 2WD, measure vacuum again. Lines should have swapped vacuum signals.
       • If No: vacuum switch bad or 4WD shift linkage needs adjusting
       • If Yes: Vacuum motor bad or stuck, or shift fork stuck: continue
5. Remove vacuum shift motor from the axle, attach vac lines to shift motor, engage/disengage 4WD. Does shift motor plunger move at least 1/2"?
   • No: shift motor bad
   • Yes: Check axle shift fork and vacuum motor for binding

This is pretty much what neattouch648 and I were having you check ... in a somewhat different order.

Trying to spin the left wheel (driver's side) checks nothing. This is a test for CAD operation. The CAD engages the collar on the right (passenger side) axle half shafts. In order to see if it's engaged, you need to try to spin the right wheel.

Read #2 above.

 

Yea I figured it all out now after posting first reading later, followed by editing and answering my own questions in my post lol. I quoted you again because you said left not right at the start, left or right isnt why I got into this thread, but being I have the answers I was after lets make sure the thread owner knows right not left.

 

You're right ... my bad ... <smack self in head ... wish I hadn't done it ... take a painkiller> RIGHT wheel.

Y'know, they teach you this stuff in the military ... you think I would get it by now.

 

glad everythings straight now RIGHT RIGHT RIGHT? lol

 

Yeah ... next time ... don't do what I said ... do what I meant!

 

Mornin!

Ok its early and very cold.
I believe I jacked up the wrong wheel as I lifted the DRIVERS side and tried to spin it.

When it warms up to 15 or 20 I will go out and jack up the pasenger side (the side with the long axel?)

Am I reading right that I should move the truck a couple feet AFEter putting it in 4 hi but before checking if the wheel spins? I think it says something like "if your light is still not on" to move it, what light? my dash indicater 4x4 light comes on when I put it in for hi.

Sammy

 

Yes, the 4WD light in the cluster. If it comes on, that means the CAD has moved enough to depress the button to light the lamp. Then, by trying to spin the RIGHT (sorry ) tire, you'll see if the collar has married the axle halves together. If it has, good to go. If it hasn't (wheel spins freely), you'll have to pull the CAD to inspect it and look inside the axle housing.