2010 Cadillac CTS Sedan AWD V6-3.6L Page 419
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) 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 module (DDM) and passenger door module (PDM) 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 mirror
heating element control circuit when a request is seen. Ground is applied through the 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 supply voltage circuit while the heated mirrors are inactive.
B1640 02
A short to ground is detected on the mirror heating element supply voltage 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 malfunction-free ignition cycles
Reference Information
Schematic Reference
Outside Rearview Mirror Schematics (See: Body and Frame/Mirrors/Diagrams/Electrical Diagrams/Outside Rearview Mirror Schematics)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Outside Mirror Description and Operation (See: Body and Frame/Mirrors/Description and Operation/Outside Mirror Description and Operation)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit
Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)
