Sierra 2500 Denali 2WD V8-6.0L (2011)
passenger seat cushion. When a driver or passenger heat or cool seat switch is pressed, a low reference signal is applied through the switch signal circuit
to the door lock/window switch. In response to the switch input, the door lock/window switch simultaneously illuminates the appropriate heated/cooled
switch indicators and sends a serial data message to the memory seat module (MSM) indicating the heat or cool seat request. The MSM then sends a
pulse width modulation (PWM) signal through the appropriate heated/cooled seat mode signal circuit to the CCSM. The CCSM then applies battery
positive voltage to the seat cushion and seat back thermal electronic devices (TEDs) and a pre-determined voltage to the blower motors. To determine
seat temperature, the CCSM supplies a 5 V signal and a low reference to the temperature sensors that are attached to each TED. The temperature sensors
are variable resistors, their resistance changes as the temperature of the seat changes. Then based on the seat temperature, the CCSM controls the voltage
level that it applies to the TEDs and blower motors.
Diagnostic Aids
The following conditions must be met in order to perform valid tests when diagnosing the climate control seat system:
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The ignition must be cycled OFF then ON between each test in order to reset the CCSM.
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Most circuit faults will set a DTC within 1.5 minutes. However, some circuit faults may cause a performance problem in one mode and be
inoperative and set a DTC in another mode. In some cases it may take 5 minutes or more for a DTC to set. Operate the heated/cooled seat in each
of the three modes for 5 minutes or more then check for DTCs.
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The engine must be running in order to supply the CCSM with the amount of current needed to operate the heated/cool seat system.
Reference Information
Schematic Reference
Heated/Cooled Seat Schematics (See: Diagrams/Electrical Diagrams)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views/Connector End Views By Name)
Description and Operation
Heated/Cooled Seats Description and Operation (See: Description and Operation/Heated/Cooled Seats)
Electrical Information Reference
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Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
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Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Connector
Repairs/Connector Repairs)
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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)
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Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning/Control Module References) for scan tool information
Circuit/System Verification
1. If both, the driver and passenger heated and cooled seats are inoperative, refer to Driver and Passenger Heated/Cool Seats Inoperative.
2. Ignition ON, observe the scan tool Driver Door Switch parameters listed below while pressing and releasing the appropriate switch. The readings
should change between Inactive and Active or Off and ON.
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Seat Back Heat Mode Sw.
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Seat Cool Mode Switch
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Seat Heat Mode Sw.
‹› If the reading does not change between Inactive and Active or Off and ON, refer to the Heated and Cooled Seat Switch component test. If the
switch tests normal, replace the driver door lock/window switch.
‹› If the readings test normal, but the driver heat/cool seat is inoperative, refer to Driver Heated/Cool Seat Circuit System Test.
3. Observe the scan tool Passenger Door Switch parameters listed below while pressing and releasing the appropriate switch. The readings should
change between Inactive and Active or Off and ON.
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Seat Back Heat Mode Sw.
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Seat Cool Mode Switch
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Seat Heat Mode Sw.
‹› If the reading does not change between Inactive and Active or Off and ON, refer to the Heated and Cooled Seat Switch component test. If the
