Heated Seat Switch/LED Indicators and System Operation

The left and right rear heated seats are controlled by separate heated seat switches located in the rear door panels. Ground is supplied to the rear heated seat switches through the switch ground circuits from their respective ground stakes. G301 for the left rear switch and G304 for the right rear switch. Battery voltage is supplied to the heated seat switch indicators through the LED dimming supply circuit from the body control module (BCM). The rear heated seat module controls the heated seat operation for both, the left and right rear heated seats, and the heated seat switch temperature indicators.

The following describes the sequence of operation and how the heated seat module responds to each of the switch inputs.

• High Temperature-When the heated seat switch is pressed once, ground is applied through the switch contacts and the switch signal circuit to the rear heated seat module indicating the high heat request. In response to this signal, the module applies battery positive through the heating element supply voltage circuits to the seat cushion and seat back heating elements. At the same time, it supplies a ground through the heating low reference circuits to the seat heating elements. The module then applies a ground through the 3 temperature indicator control circuits illuminating all 3 LEDs indicating the high temperature mode.
• Medium Temperature-When the switch is pressed a second time, the heated seat module sets the temperature level to medium heat. Then it removes the ground from the high temperature indicator leaving 2 LEDs illuminated indicating the medium temperature mode.
• Low Temperature-When the switch is pressed a third time, the heated seat module sets the temperature level to low heat. Then it removes the ground from the medium temperature indicator leaving 1 LED illuminated indicating the low temperature mode.
• System OFF State-When the switch is pressed a fourth time, the heated seat module removes the battery voltage and grounds from the heating elements. Then it removes the ground from the low temperature indicator, indicating the system OFF state.
• Back Only Mode-When the heated seat is ON and the BACK ONLY mode button is press, ground is applied through the switch contacts and the heated seat back only mode signal circuit to the rear heated seat module. In response to this signal, the module turns OFF power to the seat cushion, leaving the seat back active. The module then applies a ground through the heated seat back only mode indicator control circuit illuminating the back only mode indicator.