| • | 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. | 
Circuit  | Short to Ground  | Open/High Resistance  | Short to Voltage  | Signal Performance  | 
|---|---|---|---|---|
Mirror Heating Element Control  | B1640 02  | 1  | B1640 01  | --  | 
Ground  | --  | 1  | --  | --  | 
1. Heated Mirror Malfunction  | ||||
The driver door switch (DDS) and passenger door switch (PDS) supply voltage to the outside rearview mirror heater elements upon receipt of a serial data message from the HVAC control module indicating that the rear defrost system is active. The door module supplies B+ through the driver/passenger mirror heating element control circuit when a request is seen. Ground is applied through the driver/passenger mirror heating element ground circuit.
Outside Rearview Mirror Schematics
Outside Mirror Description and Operation
Control Module References for scan tool information
| ⇒ | If the rear window defogger indicator does not illuminate, refer to Rear Window Defogger Malfunction. | 
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the appropriate door switch. | 
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the door switch. | 
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the door switch. | 
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for DDS or PDS replacement, setup, and programming | 
| • | 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 | 
Circuit  | Short to Ground  | Open/High Resistance  | Short to Voltage  | Signal Performance  | 
|---|---|---|---|---|
Mirror Heating Element Control  | 1  | 1  | 1  | --  | 
Ground  | --  | 1  | --  | --  | 
1. Heated Mirror Malfunction  | ||||
The RR DEFOG 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.
Outside Rearview Mirror Schematics
Outside Mirror Description and Operation
Control Module References for scan tool information
| ⇒ | If the rear window defogger does not turn on, refer to Rear Window Defogger Malfunction. | 
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. | 
| ⇒ | If the test lamp is always ON, test the B+ circuit for a short to voltage. | 
| ⇒ | If the test lamp is always OFF, test the B+ circuit for a short to ground or an open/high resistance. | 
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for DDS or PDS replacement, setup and programming |