Corvette V8-7.0L (2007)
Seat Heater: Description and Operation
Heated Seats Description and Operation
The driver and front passenger heated seat systems each consists of the following components:
* Heated seat switch
* Heated seat module
* Seat cushion heater element
* Seat back heater element
* Temperature sensor
* HTDST LF Fuse 10 A
* HTDST RF Fuse 10 A
* IGN 3 RR Fuse 10 A
The HVAC control module is also involved in the operation of the heated seats.
Power and Grounds
Battery positive voltage is supplied at all times to the driver and passenger heated seat modules from the rear fuse block, HTDST LF Fuse for the driver
heated seat module, or, HTDST RF Fuse for the passenger heated seat module. This battery voltage is used by the module to apply voltage to the seat
heating elements. Battery positive voltage is also supplied to both heated seat modules from the rear fuse block IGN 3 Fuse with the ignition in the ON
position. This voltage is used to power up the module. Both modules are grounded through the ground circuit to G301. The heated seat switches are
grounded through the switch ground circuit and G201.
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 seat 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.
