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. |
DTC Descriptors
DTC B1640 01: Mirror Heater Circuit Short to BatteryDTC B1640 02: Mirror Heater Circuit Short to Ground
Circuit/System Description
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 module indicating that the rear defrost system is active. The door switch supplies B+ through the driver/passenger mirror heating element supply voltage circuit when a request is seen. Ground is applied through the driver/passenger mirror heating low reference circuit.
Conditions for Running the DTC
The heated mirrors or commanded ON
Conditions for Setting the DTC
B1640 01
A short to voltage is detected on the mirror heating element supply voltage circuit while the heated mirrors
B1640 02
A short to ground is detected on the mirror heating element supply voltage circuit while the heated mirrors
Action Taken When the DTC Sets
The affected heated mirror will not be activated.
Conditions for Clearing the DTC
| • | A current DTC will clear when the fault is no longer present |
| • | A history DTC will clear after 40 malfunction free ignition cycles |
Reference Information
Schematic Reference
Outside Rearview Mirror Schematics
Connector End View Reference
Description and Operation
Outside Mirror Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, disconnect the harness connector C1 at the outside rearview mirror.
- Ignition OFF, test for less than 300 ohms of resistance between the low reference circuit terminal 3 and ground.
- Connect a test lamp between the supply voltage circuit terminal 4 and ground.
- Ignition ON, command the mirror heater ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If all circuits test normal, test or replace the outside rearview mirror face.
| ⇒ | 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 supply voltage circuit for a short to voltage. If the circuit tests normal, replace the appropriate door switch. |
| ⇒ | If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the appropriate door switch. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for DDS or PDS replacement, setup and programming |
