For 1990-2009 cars

### Important Preliminary Checks Before Starting:

1. Perform the Diagnostic System Check - Vehicle before using the symptom tables in order to verify that all of the following are true:

• | There are no DTCs set.

• | The control modules can communicate via the serial data link

2. Review the power window system operation or rear window defogger system operation in order to familiarize yourself with the system functions. Refer to the following:

• | Rear Window Defogger Description and Operation

• | Power Windows Description and Operation

### Visual/Physical Inspection

• | Inspect for aftermarket devices which could affect the operation of the rear window defogger. Refer to Checking Aftermarket Accessories.

• | Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

### Intermittent

Important:

• | Inspect for proper installation of electrical components if an intermittent condition exists. Inspect for aftermarket theft deterrent devices, lights, and cellular phones. Ensure that no aftermarket equipment is connected to the class 2 circuit. If you can not locate an intermittent condition, a cellular phone signal may cause the condition. Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections.

• | The problem may or may not turn ON the SERVICE VEHICLE SOON indicator or store a DTC. Do not use the symptom tables to diagnose intermittent conditions. The malfunction must be present in order to locate the problem.

Poor electrical connections or wiring cause most intermittent conditions. Perform a careful visual/physical check for the following conditions:

• | Poor mating of the connector halves or a terminal not fully seated in the connector body

• | An improperly formed or damaged terminal

• | Reform or replace connector terminals in the problem circuit in order to ensure proper contact tension.

• | Poor terminal to wire connection requires removing the terminal from the connector body in order to perform the check.

Use a scan tool in order to help detect intermittent conditions. The scan tool has several features that can be used to locate an intermittent condition. The snapshot feature can capture and store data parameters within the scan tool when the malfunction occurs. This information can then be reviewed in order to see what caused the malfunction.

### Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

• | Rear Window Defogger Malfunction

• | Power Windows Malfunction