How do I troubleshoot my rear window defroster? on 2007 Audi A8 Quattro

When I press the dashboard button for the rear defroster, the light comes on and, the outside mirror defrosters, which are also controlled by the same switch, begin to defrost. I have no indication the rear window defroster is working no matter how long I wait. I don't see a fuse specified in the owners manual. Can anyone help me with this? The window grid appears to be intact.

by in Potwin, KS on December 21, 2012
1 answer 1 comment
ANSWER by , December 22, 2012
maybe there is no power to your defroster
COMMENT by , January 27, 2013
this reply states the obvious. the question is how do i troubleshoot it?