Heated Seats Description and Operation
Heated Seat Components
The driver and passenger heated seats consist of the following
components:
• |
Left heated seat switch
|
• |
Right heated seat
switch |
• |
Seat heating control
module |
• |
Driver seat cushion heating
element |
• |
Driver seat back heating
element |
• |
Driver seat cushion
temperature sensor |
• |
Passenger seat cushion heating
element |
• |
Passenger seat back heating
element |
• |
Passenger seat cushion
temperature sensor |
Power and Ground
Battery positive voltage is supplied at all times to the seat
heating control module through a 30 A fuse located in the underhood
fuse block. This voltage is used by the module to supply power to
the seat heating elements. Ground for the module is provided at
G307.
Heated Seat Operation
The driver and passenger heated seats are controlled by a single
seat heating control module that is located under the driver seat
cushion. Both 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 then serves as a gateway to
transmit the message to the seat heating control module via the
serial data line. In response to this signal, the seat heating
control module applies battery positive voltage through the element
supply voltage circuit to the appropriate seat heating elements.
The seat heating control module then 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.
Temperature Regulation
When the engine ON, the heated seats will initialize in the OFF
state. With each activation of the heated seat switch, the seat
heating control module will cycle the temperature setting in the
following manner: HIGH, MEDIUM, LOW, and OFF.
The seat heating control module monitors the seat temperature
through the temperature sensor signal circuit and the temperature
sensor (thermistor) that is located in the seat cushion. The
temperature sensor is a variable resistor, it's resistance changes
as the temperature of the seat changes. When the temperature sensor
resistance indicates to the 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.
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 .
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