common faults on alternator. on 2006 Jeep Commander

my alternator charge light comes on and only goes off at high revs,>3000 also makes whinning noise which continues and dies down after engine stops

Asked by for the 2006 Jeep Commander
sounds like a bad regulator in alt and poss a bering issue also
1 more answer
PCM regulated ,maybe have scanned to watch for proper control. Pulley poss. is 'clutched' that or bearing ,as globalhelper mentioned may also be faulty.