Yukon 4WD V8-5.3L (2008)
pressed.
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If either of the switch parameters are continuously Active or Inactive while the switch is pressed, perform the heated seat switch circuit test.
2. Verify that the MSM driver and passenger seat HVC mode and level parameters are displayed correctly as the heated seat switches are activated
through all of the operating modes.
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If the MSM parameters are not displayed correctly replace the MSM.
3. If the circuits test normal replace the driver or passenger door module.
Component Testing
1. Disconnect the heated seat switch connector at the door module.
2. Connect a fused jumper wire from the low reference circuit terminal 4 to ground.
3. Verify that a test lamp does not illuminate when connected from battery voltage to the switch signal circuit terminals 6 and 7.
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If the test lamp illuminates while the switches are in an inactive state, replace the heated seat switch.
4. Verify that a test lamp illuminates when connected from battery voltage to the switch signal circuit terminals 6 and 7 while pressing the heated seat
switches.
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If the test lamp does not illuminate while the switches are in an active state, replace the heated seat switch.
5. Verify that the heated seat switch indicators illuminate with a test lamp connected from battery voltage to the indicator control circuit terminals 1,
2, 9, 10, and 11.
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If the indicators do not illuminate replace the heated seat switch.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. See: Powertrain Management/Computers and Control
Systems/Testing and Inspection/Diagnostic Trouble Code Tests and Associated Procedures/Verification Tests and Procedures
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Front Seat Heater Switch Replacement (w/o KB6)
Heated Seat Inoperative - Rear
Heated Seat Inoperative - Rear
Diagnostic Instructions
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Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Testing and Inspection/Initial Inspection and
Diagnostic Overview/Diagnostic System Check - Vehicle
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Review Strategy Based Diagnosis for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
The rear heated seats are a high and low mode seat cushion heater system. The heater elements are controlled by the rear heated seat module mounted to
the under side of the left rear seat cushion pan. The rear heated seat switches are inputs to the rear seat audio panel and when a heated seat switch is
pressed the active switch signal is sent to the rear heated seat module through the low speed LAN circuit. The rear heated seat module determines the
heated seat mode based on the switch messages and sends a message to the rear seat audio panel to display the rear heated seat indicators as necessary.
Circuit/System Verification
1. Engine running, use a scan tool to observe the appropriate Heated Seat Switch parameter. Verify that the heated seat switch parameter changes
from Active to Inactive when the switch is pressed and released.
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If the parameter does not display the correct switch status replace the rear HVAC/RSA module.
2. Display the Rear Heated Seat Module Data list and verify that the heated temperature level changes from Off, to High, to Low as the heated seat
switch is cycled through these states.
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If the heated seat mode parameter does not change states replace the rear heated seat module.
