I had the problem with the light coming and flashing on and off... it was a vaccum line under the truck in the very center that had broken. Slid both ends into a peice of rubber tubing and problem was solved.

 

You mean when it was in 4WD, right? A broken vacuum line would not cause the light to flash when in 2WD. The switch that turns on the light is electrical and activated only when the front axle is mechanically connected by the CAD. A blinking light means a loss of vacuum that is causing the CAD to engage and disengage due to either mechanical failure or an intermittent loss of vacuum.

 

i got kinda of the same problem, my 4x4 light doesnt come on, i know its engaged because my front tires threw snow all over my tractor when i backed up, there is a 4 pin plug hanging down from my passenger side frame does that plug into the axle? i got really stuck last week and maybe it got pulled out? its not really a bother but it would be nice to know when its engaged, again