Important: The following steps must be completed before using the symptoms tables.
| • | 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 system. Refer to Checking Aftermarket Accessories . | 
| • | Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom. | 
| • | Make sure the rear parking assist sensors located on the vehicle rear bumper are clear. Remove any snow, mud or ice that is blocking the sensors. | 
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .