Seat Temperature Switch: Description and Operation
SWITCH-HEATED SEATDESCRIPTION
The heated seat switches are located in the center stack (2) of the instrument panel. The switches are located on the outer edges of the accessory switch bank (1). If either of the switches is damaged or inoperative the complete accessory switch bank assembly must be replaced.
Each heated seat switch provides a resistor-multiplexed signal to the Cab Compartment Node (CCN). Amber Light Emitting Diodes (LEDS) in the top portion of each switch indicate the level of heat in use: Two LEDs are illuminated for high, one for low, and none for off. Pressing the switch once will select high-level heating. Pressing the switch a second time will select low-level heating. Pressing the switch a third time will shut the heating elements off.
The LED indicator lamps in each heated seat switch cannot be repaired. If the LED lamps are inoperative or damaged, or the switch is inoperative or damaged the complete switch pod assembly must be replaced.
OPERATION
The heated seat switches receive battery current through a fused ignition switch output (run) circuit when the ignition switch is in the On position. Depressing the heated seat switch provides a hard-wired resistor multiplexed signal to the Cabin Compartment Node (CCN). The CCN is responsible for supplying the Controller Area Network (CAN) data bus message to the heated seat module, signaling the module to power the heated seat element of the selected seat and maintain the temperature setting.
If the heated seat switch is depressed to a different position (Low or High) than the currently selected state, the CCN will go through the process again to change the temperature setting. If a heated seat switch is depressed a second time to the same position as the currently selected state, the CCN and heated seat module interprets the second input as a request to turn the seat heater OFF. The CCN will then signal the heated seat module to turn the heated seat elements for that seat off.