2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 484
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 (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 (Heated Mirrors) (See: Body and Frame/Mirrors/Description and Operation/Outside Mirror Description
and Operation (Heated Mirrors))Outside Mirror Description and Operation (Power Mirrors) (See: Body and Frame/Mirrors/Description and
Operation/Outside Mirror Description and Operation (Power Mirrors))
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
Scan Tool References
Control Module References (See: Testing and Inspection/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 X3 harness connector at the appropriate door module.
