Circuit/System Description
WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition is turned ON, the object alarm module receives and stores the vehicle identification number (VIN) from the body control module (BCM). The BCM sends serial data messages to the object alarm module with the VIN information. The object alarm module will compare the VIN received to the VIN stored in memory. If the VIN stored in memory does not match the VIN transmitted by the BCM, the object alarm module sets a DTC and commands the red indicator ON indicating a system malfunction.