Used 4 wheel drive recently on snowy roads. The 4x4 light did not shine or was late in shutting off at different times. Any ideas? The 4 wheel drive was operating properly. Just a light issue.

Pull out the switch on the front axle.  Have someone sit in the cab, then manually push the switch in and out and verify that it is showing on the dash. 

 

I would guess that your vacuum actuator is getting weak or the shaft is bent, preventing full movement of the fork.

My shifter is on the floor...manual. I was tending towards the electrical switch that actuates the light.

Yea have someone sit in the cab and watch the light on the dash then you climb under and remove the switch from the actuator and cycle it with your finger and see if the light comes on.

Might still check the CAD unit too... I've seen where the vacuum unit could be leaking vacuum where it barely lock but not enough to trigger the light. Another is have a bent vacuum unit that is binding up the shaft preventing it to fill engage.

 

exactly what I am thinking.  

 

Verify the switch is working first then figure out why you aren't getting full throw in your vacuum actuator.

This should have been put into the 24 valve section. 

Might be a good time to install the Posi-lock system and ditch the vacuum.