For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Heated Mirror Element Control | 1 | 1 | 2 | --
Ground | -- | 1 | -- | --
1. Heated Mirror Inoperative 2. Heated Mirror Always On

### Circuit/System Description

The rear defogger relay supplies voltage to the outside rearview mirror heater elements based on the current state of the rear window defogger. The relay supplies B+ through the driver/passenger mirror heating element control circuit when a request is seen.

### Reference Information

#### Schematic Reference

Outside Rearview Mirror Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Outside Mirror Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information.

### Circuit/System Verification

1. Ignition ON, press the rear window defogger switch. Verify the rear window defogger turns ON and the rear window becomes warm.

⇒ | If the rear window defogger does not turn on, refer to Rear Window Defogger Malfunction.

2. Verify both the left and right outside mirror glass become warm.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate A9 outside rearview mirror.
2. Wait 1 minute, test for less than 10 Ω between the ground circuit terminal 7 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the heater element control circuit terminal 6 and ground.
4. Ignition ON, operate the rear window defogger ON and OFF with the rear defogger switch. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp is always ON, test the control circuit for a short to voltage.

⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance.

5. If all circuits test normal, test or replace the outside rearview mirror glass.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Outside Rearview Mirror Glass Replacement