Well I got into a sticky situation yesterday. I parked on some dirt for about 30-45 minutes and my truck sank in a little. When I went to leave it wasn't happening in 2WD. So I though no sweat pull back the "magical lever"......nope!

Got out and started checking things. Here's the list so far:

Vacuum lines @ the crossmeber where they plug into hard lines
Big 4 Vaccum line on top of X-fer Case
Vaccum lines at the frame above front axle where they go from hard to rubber again.
Vaccum lines at the CAD unit on the front axle.
Vaccum lines in the engine compartment (Thanks for walking me through that JR, there's too dang many up there)

After all that it still didn't work, and the 'ol "When in doubt........" didn't work either!

I ended up pulling the CAD unit off the front axle and sliding the collar over manually. As soon as I did this and attempted to pull out I heard a loud BANG! I stopped, checked the collar and it appeared to have moved over even more and locked in place. Tried it again and still no 4WD. All this time also the 4WD light on the dash never came on.

HELP!

 

Without putting the CAD back on the axle, attach the vacuum lines to the CAD, startup the truck and make sure the shift fork operates properly on the CAD vacuum motor shaft when you engage and disengage 4WD from the cab.

Are the little plastic wear plates still on the ends of the shift fork? If they are not, the shift collar will not move consistantly to the location where the two axles are connected and the 4WD indicator light on the dash will not light.

Make sure you look at the ends of each axle in the CAD housing. Check that the splines are smooth and the collar will slide across both axles.

The 4WD light will only light when the CAD is mounted to the axle (ground) and the shift fork is fully slid to the drivers side to activate the switch on the CAD.

I just had my system apart on my 1994. It's a pretty simple system, not a lot can go wrong here that is not easily fixed. Let me know what you find out .

PS. Did you try moving the truck without the CAD mounted to the axle, I would think that would be a dangerous thing to do? There is no way the slip collor would remain in a position to maintain the 4WD and the bang you heard might be slip collar and axle, I would really check out the ends of those two axles in the CAD axle housing.

 

Yeah I tried driving it with the cad just hanging down after I slid the collar manually. The loud bang was more than like the collar going ALL the way to the left, farther than I could get the fork to go because I couldn't get it to move at first so I was going to try and use the CAD to move it.

I just got through putting the truck up on stands. The front axle turns with the x-fer case locked in 4WD, but the front tires will not turn. However I had it in 4WD yesterday with the collar slid manually and it still would not turn the front tires.

 

Let me get this right......The front output shaft is turning when the TC is engaged but neither tire will turn?

If you say the axle is turning it should be turning at least one tire, there is no locking hubs on these trucks to keep the wheels from spinning, they are in essence "locked in" all the time.

You should be able to spin your drivers side tire by hand and see the axle turning because the axle should be moving anytime the wheel turns.

 

Hmm. So you put the axle in 4wd by hand, and tried it, and still no go? If so, sounds like something is broken? Does the 4wd indicator ever light up? When the shaft in the unit that bolts to the axle slides over is when the 4wd indicator light comes on. We have had my buddies 95 apart, and that is how it works. What if you spin one front wheel with it in 4wd? Does the other spin the opposite direction? If not; it must not be locked in? Not sure but good luck

Eric