Circuit Description
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Modules connected to the Class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules.
In addition, Node Alive and State of Health messages are transmitted by each module on the Class 2 serial data circuit about once every 2 seconds. When a module does not detect a message on the Class 2 serial data circuit for approximately 3 seconds. Without low or high voltage detected, the U1305 is set. The setting of all other Class 2 serial communication DTCs is inhibited.