Front Heated Seat Malfunction
Front Heated Seat Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The left and right heated seats are controlled by the memory seat module (MSM). When active, ground is applied to the seat cushion and back heater elements through a common low side drive low reference control circuit. Battery voltage is applied to the seat cushion and seat back heater elements by the MSM through separate high side drive control circuits. In the back only mode, the MSM applies battery voltage to just the seat back heater element, not the seat cushion heater element. The heater element control circuits are pulse width modulated to B+ by the module in order to control the seat temperature by regulating the current flow through the heater elements. The module then monitors the current flow through the heating elements and the of rate change of the temperature sensors to verify correct heated seat operation.
Reference Information
Schematic Reference
Heated/Cooled Seat Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Heated Seats Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool Driver Door Module and Passenger Door Module heated seat switch parameters listed below while pressing and releasing the appropriate switch. The readings should change between Inactive/Off and Active/On.
* Heated Seat Switch
* Back Only Heat Switch
• If not the specified value, replace the appropriate door module.
2. Observe the scan tool Driver Seat Module heat zone parameters listed below while pressing the appropriate heated seat switch listed above. The readings should change between Off and Back/Cushion or Back Only.
* Driver Seat Heat Zone
* Psgr. Seat Heat Zone
• If not the specified value, replace the MSM.
3. Observe the scan tool Driver Seat Module temperature setting parameters listed below while pressing the appropriate heated seat switch through the high, medium, and low temperature settings. The readings should change between Off, High, Med, and Low.
* Driver Seat Temp. Setting
* Psgr. Seat Temp. Setting
• If not the specified values, replace the MSM.
4. Observe the appropriate heated seat switch mode and temperature indicators while pressing the appropriate heated seat switch. The appropriate indicators should illuminate.
• If any of the indicators do not illuminate, replace the appropriate door module.
5. If all scan tool parameters test normal, refer to Circuit/System Testing
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the appropriate seat heater element.
2. Connect a test lamp between control circuit terminal A and control circuit terminal B.
3. Ignition ON, press the heated seat switch. The test lamp should illuminate.
• If the test lamp does not illuminate, test the control circuits for a short to ground or an open/high resistance. If the circuits test normal, replace the MSM.
4. If all circuits test normal, test or replace the seat heater element.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Driver or Passenger Seat Back Cushion Heater Replacement (Driver or Passenger Seat Back Cushion Heater Replacement)
* Driver or Passenger Seat Cushion Heater Replacement (Driver or Passenger Seat Cushion Heater Replacement)
* Control Module References (Programming and Relearning) for MSM, DDM, and PDM replacement, programming, and setup