2003 Cadillac CTS Service Charging System
 

I have a 2003 Cadillac CTS. Battery went completely dead and car stalled. Charged battery (a slow full charge) car started and runs fine but panel shows Service Charging System. I had the Battery and alternator checked Battery check good but the guy checking said something in the charging system but did not sat alternator pacific and did not have paper in his device to print out a detailed check list. I just want to be sure before I have a alternator installed that all other possibilities have been ruled out. Thanks for any help you may have.