Heated Seat Operation
WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.
The driver and passenger heated seats are controlled by separate heated seat switches. Both switches are located in the HVAC control module. When a heated seat switch is pressed, the HVAC control module sends a class 2 message to the body control module (BCM) indicating the heated seat command. In response to this signal, the BCM applies battery positive voltage through the heated seat relay control circuit energizing the relay. The relay closes its switch contacts applying battery positive voltage through the element supply voltage circuit to the seat heating elements. The BCM then sends a class 2 message back to the HVAC control module to illuminate the appropriate temperature indicator.