I just noticed that on my 01 Tahoe, the passenger side mirror doesn't defrost when I turn on the defogger, the driver's side works fine. Can I fix the defogger on the mirror? or I must replace the whole side mirror, thanks.

 

Have you checked the fuse yet???

 

Someone said wiring/connectors were the most likey cause of the problem since there aren't any moving pieces. Trace them before you go the mirror route.