RSE Outputs
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
At minimum volume, the plus (+) and minus (-) audio signals are approximately half battery voltage, measured to vehicle ground. These audio signals are sent from the radio to the Infrared Module, most systems have a common minus (-) signal.