The actual case isn't activated by the vaccum system at all... ie. the case doesn't start changing once the vaccum system says its activated or vice versa.
So I can't see theis being a problem.
However the light will also flash if the case doesn't engage properly, but unless you've pulled you case apart, the only reason it would do this is if the 4x4 switches on the case shat themselves.
I reckon you have a crack in one of the hoses. Costs about $3 worth of hose and half hour to pull each piece off, cut it to length and plug it all back in
