Corvette V8-6.2L (2008)
Seat Heater: Description and Operation
Heated Seats Description and Operation
The driver and passenger heated seats each consists of the following components:
*
Heated seat switch
*
Heated seat module
*
Seat cushion heater element
*
Seat back heater element
*
Temperature sensor
*
DRVR HTD SEAT fuse 20 amp
*
PASS HTD SEAT fuse 20 amp
*
HTD SEAT/WPR RLY fuse 10 amp
Power and Ground
Battery voltage is supplied at all times to the heated seat modules through the DRVR HTD SEAT fuse and the PASS HTD SEAT fuse located in the IP
fuse block. This voltage is used by each module to supply power to the seat cushion and seat back heating elements. Each heated seat module is also
supplied with battery voltage through the HTD SEAT/WPR RLY fuse located in the body control module (BCM) which is controlled by the RUN
CRANK relay. This voltage is used to power up each heated seat module and allows the heated seat system to operate only with the ignition in the ON
position. Each heated seat module is grounded through the module ground circuit at G301 for the driver seat and G302 for the passenger seat.
Temperature Regulation
The heated seat system is designed in order to warm the seat cushion and seat back to approximately 107.6°F (42°C) when in the high position, and 98.6°
F (37°C) when in the low position. The heated seat 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. Its resistance changes as the temperature
of the seat changes. When the temperature sensor resistance indicates to the heated seat 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.
Heated Seats
The driver and passenger heated seats are controlled by separate heated seat switches. When the heated seat is OFF and the heated seat switch is toggled
toward HI/LO, the heated seat high/low signal circuit of the heated seat module is momentarily grounded through the HI/LO switch contacts. In response
to this signal, the heated seat module applies battery positive voltage to the seat cushion/back heater elements, setting the temperature level to high heat.
The module also applies battery positive voltage through the heated seat high temperature indicator control circuit to illuminate the high temperature
indicator of the heated seat switch. When the heated seat switch is toggled toward HI/LO a second time, the heated seat high/low signal circuit of the
heated seat module is again momentarily grounded through the HI/LO switch contacts. In response to this second signal, the heated seat module sets the
temperature level to low heat and applies battery positive voltage through the heated seat low temperature indicator control circuit to illuminate the low
temperature indicator of the heated seat switch. When the heated seat switch is toggled toward OFF, the heated seat off signal circuit of the heated seat
module is momentarily grounded through the OFF switch contacts. In response to this signal, the heated seat module removes the battery voltage from
the seat heating elements and the appropriate temperature indicator. The heated seat module will also turn OFF the heated seat whenever the ignition
switch is turned to the OFF position.
Load Management
There are 3 levels of load management controlled by the body control module (BCM). The BCM sends the status of load management to the HVAC
control module via a class 2 message. In response to this message, the HVAC control module signals the heated seat modules through the heated seat
module inhibit signal circuit indicating the current load management level. During load shed 0, the HVAC control module does not inhibit the operation
of the heated seats. During load shed level 1, the heated seats are cycled 10 seconds ON and 10 seconds OFF, with temperature regulation still being
enforced. During load shed level 2, the HVAC control module will pull the inhibit signal circuit of the heated seat module to ground. In response to this
signal, the heated seat modules will turn OFF the heated seats and temperature indicators that are illuminated. The instrument panel cluster (IPC) will
display a BATTERY SAVER ACTIVE message. The ON/OFF status of the heated seats is reported to the HVAC control module through the heated
seat control module status signal circuit by both heated seat modules.
