Heated Seat Components
The heated seats consist of the following components:
| • | Left heated seat control module |
| • | Left heated seat switch |
| • | Left seat cushion heating element |
| • | Left seat back heating element |
| • | Left seat cushion temperature sensor |
| • | Right heated seat control module |
| • | Right heated seat switch |
| • | Right seat cushion heating element |
| • | Right seat back heating element |
| • | Right seat cushion temperature sensor |
Modes of Operation
Both front heated seats are controlled independently of one another and each
heated seat has its own heated seat module (HSM). The heated seats have only one mode
of operation. The heated seat cushion base and the heated seat back cannot operate
independently of one another.
Heated Seat Switch/LED Indicators Operation
Ignition voltage is supplied to the heated seat switch fuse via fuse F38/10A
located in the under-hood fuse block. The body control module (BCM) supplies voltage
to the heated seat switch LEDs and the heated seat module (HSM) supplies a ground
signal to the heated seat switch LEDs.
The heated seat switch indicates 3 heat level settings.
| • | Low Temperature - When the heated seat switch is depressed once,
ignition voltage is supplied via the heated seat switch contacts and the heated seat
switch signal circuit to the HSM. The HSM then supplies a ground signal to one of
the heated seat switch LEDs to indicate that the first heating level is active. |
| • | Medium Temperature - When the heated seat switch is depressed for
the second time, ignition voltage is supplied via the heated seat switch contacts
and the heated seat switch signal circuit to the HSM. The HSM then supplies a ground
signal to the second LED of the heated seat switch. Two LEDs will be lit indicating
that the second heating level is active. |
| • | High Temperature - When the heated seat switch is depressed for
a third time, ignition voltage is supplied via the heated seat switch contacts and
the heated seat switch signal circuit to the HSM. The HSM then supplies a ground signal
to the third LED of the heated seat switch. Three LEDs will be lit indicating that
the third heating level is active. |
| • | System OFF State - When the heated seat switch is depressed for
a fourth time, ignition voltage is supplied via the heated seat switch contacts and
the heated seat switch signal circuit to the HSM. The HSM then switches OFF the ground
supply to the LEDs. No LEDs will be lit indicating that the heated seat system is
in the OFF state. |
Heated Seat module Operation
A continuous battery voltage is supplied to both heated seat modules via fuse
F19/15A located in the instrument panel (I/P) fuse block. Ignition voltage is supplied
to both heated seat modules via fuse F38/10A located in the under-hood fuse block.
Ground for both heated seat modules are supplied via G305 and G304 respectively.
The three heat level settings of the heated seats are selected by depressing
the heated seat switch consecutively. Upon depressing the heated seat switch for the
fourth time, the heated seat will switch OFF.
Depending on the heat level selected, the HSM supplies voltage to the seat cushion
base and the seat back elements. The different temperature levels of the seat cushion
base and the seat back elements are monitored by the HSM via a temperature sensor.
When the seat cushion base and seat back heating elements reach a predetermined value
stored within the HSM, the voltage supply to the seat cushion base and seat back heating
elements are switched OFF. When the temperature drops below a predetermined value
stored within the HSM, the HSM switches the voltage to the seat cushion base and seat
back heating elements ON, thereby regulating the temperature. The HSM supplies a ground
signal to the first LED of the heated seat switch and level one setting is shown as
active.
Temperature Regulation
The HSM regulates the heated seat temperature in accordance with the input values
of the thermister which is situated in the seat cushion base close to the seat heating
element.
Thermisters are variable resistors. Their resistance varies as temperature changes.
When the thermister resistance reach a predetermined value stored within the HSM,
the HSM switches the voltage to the seat cushion base and seat back heating elements
OFF. When the temperature drops below a predetermined value stored within the HSM,
the HSM switches the voltage to the seat heating elements ON, thereby regulating the
seat cushion base and seat back heating element temperatures.
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 discharged
condition. The heated seat system is one of the vehicle loads that is subject to being
switched OFF during a battery discharged condition. For more information on load management
refer to
Electrical Power Management Description and Operation
.
