Silverado 1500 4WD V8-6.0L Hybrid (2009)
Seat Heater: Symptom Related Diagnostic Procedures
Symptoms - Seat Heating and Cooling
Symptoms - Seat Heating and Cooling
Important: The following steps must be completed before using the symptom tables.
1. Perform theDiagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) before using the Symptom Tables in order to verify that all of the following are true:
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There are no DTCs set.
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The control modules can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to Heated Seats Description and Operation (See:
Description and Operation/Heated Seats Description and Operation) .
Visual/Physical Inspection
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Inspect for aftermarket devices which could affect the operation of the system. Refer to Checking Aftermarket Accessories (See: Testing and
Inspection/Component Tests and General Diagnostics) .
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Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections (
See: Testing and Inspection/Component Tests and General Diagnostics) .
Symptom List
Refer to Heated Seat Inoperative (See: Heated Seat Inoperative) in order to diagnose the symptom.
Heated Seat Inoperative
Heated Seat Inoperative
Diagnostic Instructions
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Perform theDiagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
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ReviewStrategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
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Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure Instructions)
provides an overview of each diagnostic category.
Circuit/System Description
The driver and front passenger heated seats are controlled by separate heated seat switches located on the door panels. When a heated seat switch is
pressed, ground is momentarily applied through the switch contacts and the switch signal circuit to the door lock/window switch. In response to this
signal, the door lock/window switch sends a serial message to the memory seat module (MSM) indicating the heat seat request. The MSM then applied
battery voltage to the seat cushion and seat back heater elements through a common voltage supply circuit. Each individual heater element is grounded
by the module through separate low side drive control circuits. The heater element control circuits are pulse width modulated (PWM) to ground by the
module in order to control the seat temperatures by regulating the current flow through the heater elements. The MSM relies on 4 independent inputs
from temperature sensors (thermistors) located in the seat back and seat cushion of the driver and passenger seats. The temperature sensor resistance
varies based on the temperature of the heating element causing the signal circuit voltage to change. Once the seat reaches the switch set temperature, the
MSM will then cycle the control circuits of the heating elements ON and OFF in order to maintain the desired seat temperature based on the feedback
voltage from the sensors. The MSM then monitors the current flow through the heating elements and the of rate change of the temperature sensor to
verify correct heated seat operation.
Reference Information
Schematic Reference
Heated/Cooled Seat Schematics (See: Diagrams/Electrical Diagrams)
Connector End View Reference
