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
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Mirror Heating Element Supply Voltage | B1640 02 | 1 | B1640 01 | -- |
Low Reference | - | 1 | 1 | -- |
1. Heated Mirror Malfunction | ||||
Circuit/System Description
The Driver Door Module (DDM) and Passenger Door Module (PDM) supply voltage to the outside rearview mirror heater elements upon receipt of a message from the HVAC 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 low reference circuit.
Conditions for Running the DTC
Battery voltage must be between 9-16 volts.
Conditions for Setting the DTC
B1640 01
A short to voltage is detected on the mirror heating element control circuit while the heated mirrors are inactive.
B1640 02
A short to ground is detected on the mirror heating element control circuit while the heated mirrors are active.
Action Taken When the DTC Sets
The heated mirror will be disabled.
Conditions for Clearing the DTC
| • | A current DTC will clear when the fault is no longer present. |
| • | A history DTC will clear after 40 fault 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
| • | Circuit Testing |
| • | Wiring Repairs |
Scan Tool References
Control Module References for scan tool information.
Circuit/System Verification
Ignition ON, press the rear window defogger switch. The rear window defogger and both heated mirrors should become warm.
Circuit/System Testing
- Ignition OFF, disconnect the X3 harness connector at the appropriate door module.
- Ignition ON, verify a test lamp does not illuminate between the control circuit terminal 7 and ground.
- Ignition OFF, test for infinite resistance between the control circuit terminal 7 and ground.
- Test for 5-10 ohms of resistance between the control circuit terminal 7 and the low reference circuit terminal 3.
- If all circuits test normal, test or replace the door module.
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
| ⇒ | If less than the specified value, test the control circuit for a short to ground. If the circuit tests normal, test or replace the applicable rearview mirror face. |
| ⇒ | If not within the specified range, test the control circuit and the low reference circuit for an open/high resistance. If the circuits test normal, test or replace the appropriate rearview mirror face. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for DDM or PDM replacement, setup and programming |
