Important: 
   •  There are no DTCs set.    •  The control modules can communicate via the serial data link. 
| • | Inspect for aftermarket devices which could affect the operation of the Entertainment System. Refer to Checking Aftermarket Accessories . | 
| • | Inspect for easily accessible or visible system components for obvious damage or conditions which could cause the symptom. | 
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom: