DTC U1300: Class 2 Circuit (Short To Ground): Description
Serial data link is used to communicate information and commands between modules. In addition, Node Alive (State Of Health) messages are transmitted by each module on the serial data link about once every 2 seconds. When a module detects no messages and a low voltage on the serial data link for about 3 seconds, DTC U1300 is set, the setting of all other class 2 serial communication DTCs is inhibited and the module uses default values for all parameters received on the class 2 serial data link.
A current DTC U1300 will clear when a valid class 2 message is detected on serial data link or at the end of the current ignition cycle. A history DTC U1300 can only be cleared using scan tool.