B1640

DTC B1640

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



DTC Descriptors
DTC B1640 01
- Mirror Heater Circuit Short to Battery

DTC B1640 02
- Mirror Heater Circuit Short to Ground




Diagnostic Fault Information






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 (Outside Rearview Mirror Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Outside Mirror Description and Operation (Heated Mirrors) (Outside Mirror Description and Operation (Heated Mirrors))Outside Mirror Description and Operation (Power Mirrors) (Outside Mirror Description and Operation (Power Mirrors))
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool References

Programming and Relearning (Programming and Relearning)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

1. Ignition OFF, disconnect the harness connector X3 at the appropriate door switch.
2. Ignition ON, verify a test lamp does not illuminate between the supply voltage circuit terminal 7 and ground.

• If the test lamp illuminates, test the supply voltage circuit for a short to voltage.

3. Ignition OFF, test for infinite resistance between the supply voltage circuit terminal 7 and ground.

• If less than the specified value, test the supply voltage circuit for a short to ground. If the circuit tests normal, test or replace the applicable rearview mirror face.

4. Test for 5-10 ohms of resistance between the supply voltage circuit terminal 7 and the low reference circuit terminal 3.

• If not within the specified range, test the supply voltage circuit and the low reference circuit for an open/high resistance. If the circuits test normal, test or replace the appropriate rearview mirror face.

5. If all circuits test normal, test or replace the appropriate door switch.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Outside Rearview Mirror Glass Replacement (Outside Rearview Mirror Glass Replacement)
* Programming and Relearning (Programming and Relearning)for DDS or PDS replacement, setup and programming