The driver and front passenger heated seats each consist of the following components.
• | Climate Control Panel (CCP) |
• | Body Control Module (BCM) |
• | Seat Cushion Heater Element |
• | Seat Back Heater Element |
Power and Ground
Battery positive voltage is supplied at all times to both front heated seat
relays from the HEATED SEAT Fuses located in the IP fuse panel. Both relays are grounded
through the relay ground circuits and G301.
Heated Seat Operation
The driver and passenger heated seats are controlled by separate heated seat
switches. Both switches are located in the climate control panel (CCP). When a heated
seat switch is pressed, the CCP sends a class 2 message to the body control
module (BCM) indicating the heated seat command. In response to this signal, the BCM
applies battery positive voltage through the heated seat relay control circuit energizing
the relay. The relay closes its switch contacts applying battery positive voltage
through the element supply voltage circuit to the seat heating elements. The BCM then
sends a class 2 message back to the CCP to illuminate the appropriate temperature
indicator.
Temperature Regulation
When the ignition is turned to the ON position, the heated seats will initialize
in the OFF state. With each activation of the heated seat switch, the body control
module (BCM) will cycle temperature setting in the following manner: HIGH, LOW, and
OFF.
The heated seat system is designed in order to warm the seat cushion and seat
back to approximately 42°C (107.6°F) when in the high heat position, and 37°C
(98.6°F) when in the low heat position. The BCM 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,
its resistance changes as the temperature of the seat changes. When the temperature
sensor resistance indicates to the BCM that the seat has reached the desired temperature,
the module removes battery voltage from the heated seat relay control circuit de-energizing
the relay. The relay then opens it's switch contacts removing battery voltage from
the heated seat element supply voltage circuit and the seat heating elements. The
module will then cycle the relay control circuit on and off in order to maintain the
desired temperature.
Load Management
During Heated Seats Load Shed Level 1, the body control module (BCM)
will cycle the heated seat operation 16.0 seconds ON and 4.0 seconds
OFF. During Heated Seats Load Shed Level 2, the BCM will deactivate the heated
seat operation, and signal the climate control panel (CCP) turn off the
appropriate heated seat temperature indicators.