Steering Wheel Controls
WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
The steering wheel controls for the HVAC system include air temperature and blower motor speed adjustments. Pressing the up arrow on the air temperature switch increases the outlet air temperature. Pressing the down arrow on the air temperature switch decreases the outlet air temperature. The body control module (BCM) receives the input from the steering wheel controls. Pressing one of the steering wheel switches enables an in line resistor to drop voltage on the remote radio control signal circuit. The BCM then interprets this voltage signal and sends a class 2 message to the HVAC control module for the desired change.