Heated/Vented Seat Description and Operation
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Heated/Vented Seat Description and Operation
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The heated/vented seat system consists of the following components:
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Seat memory control module or seat heating control module
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Seat cushion heating element
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Seat back heating element
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Seat cushion temperature sensor
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Seat cushion blower motor
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The driver and passenger heated seats are controlled by separate heated seat switches that are located in the HVAC control. When a heated seat switch is pressed, a serial data message is sent from the HVAC control to the HVAC control module indicating the heated seat command. The HVAC control module serves as a gateway to transmit the message to the seat memory control module/seat heating control module via the serial data line. In response to this message, the seat memory control module/seat heating control module applies battery voltage through the element supply voltage circuit of the seat heating elements. The seat memory control module/seat heating control module sends a serial data message back to the HVAC control module to gateway the information to the HVAC control to either illuminate or turn off the appropriate temperature indicator.
The seat memory control module/seat heating control module monitors the seat temperature through the temperature sensor signal circuit and the temperature sensor (thermistor) located in the seat cushion with the heater element. The temperature sensor is a variable resistor, it's resistance varies as the temperature of the seat changes. When the temperature sensor resistance indicates to the seat memory control module/seat heating control module 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.
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 HVAC controls. With the ignition ON, Ignition voltage is supplied to the driver and passenger seat blower motors through a 10 A fuse located in the underdood fuse block. Ground is provided to the driver and passenger seat blower motors from G305. When a vented seat switch is pressed, a serial data message is sent from the HVAC control to the HVAC control module indicating the vented seat command. The HVAC control module serves as a gateway to transmit the message to the seat memory control module/seat heating control module via the serial data line. In response to this message, the seat memory control module/seat heating control module 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 seat memory control module/seat heating control module then sends a serial data message back to the HVAC control module to gateway the information back to the HVAC control to either illuminate or turn off the appropriate switch indicator.
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
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