Seat Temperature Element: Description and Operation

Heated/Vented Seat Description and Operation

Heated Seat Components

The heated seats consist of the following components:

* Left heated seat switch
* Right heated seat switch
* HVAC control panel
* Memory seat module
* Left seat cushion heating element
* Left seat back heating element
* Left seat cushion temperature sensor
* Right seat cushion heating element
* Right seat back heating element
* Right seat cushion temperature sensor



Heated Seat Operation

The driver and passenger heated seats are controlled by separate heated seat switches. Both switches are located in the CCP. When a heated seat switch is pressed, the CCP sends a class 2 message via the serial data line to the memory seat module (MSM) indicating the heated seat command. In response to this signal, the MSM then applies or removes battery voltage through the element supply voltage circuit of the seat heating elements. The MSM then sends a class 2 message back to the CCP to either illuminate or turn off the appropriate temperature indicator.


Temperature Regulation

The heated seat system is designed to warm the seat cushion and seat back to approximately 42°C (107.6°F) when in the high position, 39.5°C (103°F) when in the MED position, and 37°C (98.6°F) when in the low position. The memory seat module (MSM) monitors the seat temperature through the temperature sensor signal circuits and the temperature sensors (thermistor) that are located in the seat cushion and the seat back. The temperature sensors are variable resistors, their resistance varies as the temperature of the seat changes. When the temperature sensor resistance indicates to the MSM 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 (Description and Operation) .