Audio Systems: CLARION RDC634 ERR 9, rf antenna, antenna connection

Question
CLARION RDC634 ERR 9 WHAT IS THIS & CAN I FIX IT?

Answer
Here is a nice discussion on your very problem:

http://www.fixya.com/support/t158274-clarion_rdc634_error_9

According to this comment the problem relates to poor rf/antenna connection or signal into the front end of the unit.  If the car has an automatic antenna or a bad antenna cable it could be contributory to the problem.

Hope this helps.

C