U1300
U1300 - Class II Data Link LowModules connected to the Class II serial data circuit monitor for serial data communication during normal vehicle operation. Operating information and commands are exchanged among the modules. In addition to this, Node Alive (State of Health) messages are transmitted by each module on the Class II serial circuit about once every 2 - 5 seconds. When the module detects no messages and a low voltage on the Class II serial data circuit for approximately three seconds, U1300 is set and the setting of all other communication DTCs is inhibited.
Diagnostic Aids
^ This code is checked for and will set if the voltage supplied to the modules is between 9 - 16 volts. If there are no valid Class II messages on the Class II line for 3 seconds or if the voltage level on the Class II data circuit is low for 3 seconds, this code will set.
^ This DTC cannot be retrieved with a current status. Diagnosis of a history U1300 is accomplished via the symptom No Communication On Class II Data Link
^ An intermittent is diagnosed by using the No Communication On Class II Data Link procedure to isolate an intermittent short to ground.
^ A current U1300 will clear when a valid Class II message is detected on the Class II serial data circuit or at the end of the current ignition cycle.
^ A history U1300 will clear upon completion of 100 ignition switch ON/OFF cycles with no repeated malfunction. When this DTC sets, all other DTCs are inhibited.