Important: The following steps must be completed before
using the symptom tables.
- Perform the 
Diagnostic System Check - Vehicle 
 in Vehicle DTC Information, before
using the symptom tables in order to verify that all of the following are true:
 
| •  | The body control module (BCM) can communicate via the serial data link. | 
 
- Review the system operation in order to familiarize yourself with the
system functions. Refer to the following:
 
Visual/Physical Inspection
Several of the symptom procedures ask for a careful visual/physical check.
This step is extremely important-it could lead to correcting a problem 
 without further checks and can save valuable time. These checks 
 include the following:
|     •  | Inspect the easily accessible or visible system components and harness
connectors for obvious damage or conditions which could cause the 
 symptom. | 
 
|     •  | If only one lamp is inoperative, inspect and repair a poor connection
 or an open in the power feed or ground circuit before replacing the light 
 bulb. Refer to 
Circuit Testing 
 and 
Wiring Repairs 
 in Wiring Systems. | 
 
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to
diagnose a symptom that does not set a DTC: