Circuit Description
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The Body Control Module (BCM) internally grounds the door unlock relay control circuit for the rear door unlock relay when it receives a Class 2 message from the Driver Door Module (DDM) or Passenger Door Module (PDM). When the BCM grounds the door unlock relay control circuit the rear door unlock relay is energized and unlocks the rear doors.