Important: For the inside rearview mirror with the automatic day-night feature, review
the system operation in order to familiarize yourself with the system functions. Refer
to 
Automatic Day-Night Mirror Description and Operation 
 .
For the rear window defogger system, the following steps must be performed 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 control modules can communicate via the serial data link. | 
 
- Review the system operation in order to familiarize yourself with the
system functions. Refer to 
Rear Window Defogger Description and Operation 
 .
 
Visual/Physical Inspection
|     •  | Inspect for aftermarket devices which could affect the operation of the
rear window defogger or the automatic day-night feature of the inside rearview mirror.
Refer to 
Checking Aftermarket Accessories 
 in
Wiring Systems. | 
 
|     •  | Inspect the easily accessible or visible system components for obvious
damage or conditions which could cause the symptom. | 
 
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions.
Refer to 
Testing for Intermittent Conditions and Poor Connections 
 in Wiring Systems.
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to
diagnose the symptom: