Circuit/System Description

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

The driver and front passenger vented seats are controlled by separate vented seat switches that are located in the S48A Multifunction Switch - Instrument Panel. When a vented seat switch is pressed, a LIN Bus serial message is sent from the S48A Multifunction Switch - Instrument Panel to the K9 Body Control Module. The K9 Body Control Module serves as the heated/vented seat system master to determine the requested operating mode. The K9 Body Control Module then sends a LIN bus serial data message to the K29F Front Seat Heater Control Module indicating the vented seat command.

In response to this message, the K29F Front Seat Heater Control Module applies a low side drive pulse width modulation (PWM) signal through the blower motor control circuit to the seat back and cushion blower motors indicating the seat ventilation command. The logic in the blower motors sets the blower speed to the switch set point. The K9 Body Control Module then sends a serial data message back to the S48A Multifunction Switch - Instrument Panel to either illuminate or turn off the appropriate temperature indicator.