Vehicle/Powertrain Control Module

WARNING: This page is about a different car, the 2003 GMC Sonoma, 2003 GMC Jimmy, 2003 Chevrolet S10 Pickup, and 2003 Chevrolet Blazer. However, it is still accessible from the selected car via links, so may be relevant.

The VCM/PCM communicates with the BCM over the Class 2 serial data line. When the BCM determines a no start condition, it sends a Class 2 serial data password to the VCM/PCM in order to disable the fuel injection system. If the BCM receives the expected voltage from the Passlock™ sensor, the BCM sends a class 2 serial data password to the VCM/PCM in order to enable the fuel injection system. The VCM/PCM then allows the vehicle to start correctly. If the Class 2 serial data password from the BCM to the VCM/PCM is not within the Vehicle Security Status Message, the fuel injectors will shut OFF during a start attempt. The SECURITY telltale will be illuminated for 10 minutes. If the VCM/PCM does not receive the same password from the BCM as the last learned one, the vehicle will start and then stalls due to the Fuel Lockout.