Diagnostic Trouble Codes (DTCs)
WARNING: This page is about a different car, the 2004 Pontiac Sunfire and 2004 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
Each control module connected to the class 2 serial data circuit monitors serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. In addition, node alive messages are transmitted by each module on the class 2 serial data circuit about once every 2 seconds. If a module does not receive a node alive message when expected, a DTC will set. If a module detects that the class 2 serial data circuit is shorted, the setting of all other class 2 serial communication DTCs is inhibited, and DTC U1300, U1301, or U1305 will set.