Yesterday when I shifted out of 4WD I noticed that the light stays on, I haven't been able to get it to shut off since. I am fairly certain the the CAD is still working however, because when I'm in 2wd I can turn without the front axle clicking. I have good vacuum at for the line going down of the engine, I haven't check the other lines though, but as I said, I didn't think the cad would work without vacuum. Is this a dirty connection somewhere or is the truck telling me i have a 4wd problem?

Also 4wd does engage without any fuss

 

You might check your vacuum lines at the CAD housing.
Sometimes they can break causing the 4WD light to come on.

 

i just solved this problem in my truck yesterday...vacuum line came loose

 

the little vaccuum unit on the axle itself may be stuck in the 4x4 position, it is only a switch on the inside of the axle housing. Might be worth a check.