CTS Sedan AWD V6-3.0L (2010)
Seat Heater: Description and Operation
Heated/Vented Seat Description and Operation
Heated Seat Components
The heated seats consist of the following components:
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Left heated seat switch
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Left vented seat switch
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Right heated seat switch
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Right vented seat switch
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HVAC control panel
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Memory seat module
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Left seat cushion heating element
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Left seat back heating element
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Left seat cushion temperature sensor
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Right seat cushion heating element
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Right seat back heating element
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Right seat cushion temperature sensor
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MISC IGN Fuse 10 A
Heated Seat Operation
The driver and passenger heated seats are controlled by separate heated seat switches. Both switches are located in the integrated center stack (ICS).
When a heated seat switch is pressed, a message is sent via the CAN graphical interface (CGI) serial data line to the radio. The radio then serves as a
gateway to transmit the message to the memory seat module (MSM) via GMLAN serial data indicating the heated seat command. In response to this
signal, the MSM then applies or removes battery voltage through the element supply voltage circuit of the seat heating elements. The MSM then sends a
serial data message back to the radio to gateway the information to the ICS to either illuminate or turn off the appropriate temperature indicator.
Temperature Regulation
The heated seat system is designed to warm the seat cushion and seat back to 3 different temperature settings; High, MED, and Low. The memory seat
module (MSM) monitors the seat temperature through the temperature sensor signal circuits and the temperature sensors (thermistor) that are located in
the seat cushion and the seat back. The temperature sensors are variable resistors, their resistance varies as the temperature of the seat changes. When the
temperature sensor resistance indicates to the MSM that the seat has reached the desired temperature, the module opens the ground path of the seat
heating elements through the heated seat element control circuit. The module will then cycle the element control circuit open and closed in order to
maintain the desired temperature.
Vented Seat Operation
The vented seat operation is designed to draw cabin air around and away from the occupant through small holes in the seat cushion and seat back covers,
through channels in the foam pad, and then through the blower motor exhausting the waste air under the seat cushion.
The driver and passenger vented seats are controlled by separate vented seat switches located in the integrated center stack (ICS) with the radio and
HVAC controls. With the ignition ON, Ignition voltage is supplied to the driver and passenger seat blower motors through the MISC IGN fuse located in
the underhood fuse block. Ground from G200 is provided to the driver seat blower motors, while G201 provides ground for the passenger seat blower
motors. When a vented seat switch is pressed, a message is sent via the CAN graphical interface (CGI) serial data line to the radio. The radio then serves
as a gateway to transmit the message to the memory seat module (MSM) via the GMLAN serial data line indicating the vented seat command. In
response to this message, the MSM applies a low side pulse width modulation (PWM) signal through the blower motor control circuits to the seat
cushion and seat back blower motors indicating the vented seat command. The logic in the blower motors then sets the blower speed to the switch set
point. Both blower motors run drawing cabin air around and away from occupant. The MSM then sends a serial data message back to the radio to
gateway the information back to the ICS to either illuminate or turn off the appropriate switch indicator.
Load Management
The electrical power management function is designed to monitor the vehicle electrical load and determine when the battery is potentially in a high
discharge condition. The heated seat system is one of the vehicle loads that is subject to reduction during a battery discharge condition. For more
information on load management refer to Electrical Power Management Description and Operation (See: Starting and Charging/Description and
Operation/Electrical Power Management Description and Operation).
