Circuit Description
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 to
this, Node Alive (State of Health) messages are transmitted by each module
on the class 2 serial data circuit approximately once every 2 seconds.
When a module detects no messages and a low voltage on the class 2
serial data circuit for approximately 3 seconds, U1300 is set. The
setting of all other class 2 serial communication DTCs is inhibited.
Conditions for Running the DTC
| • | Voltage supplied to the module is in the normal operating voltage
range (approximately 9-16 volts). |
| • | Module operation requires serial data communication to occur. |
Conditions for Setting the DTC
| • | No valid messages are detected on the class 2 serial data
circuit. |
| • | The voltage level detected on the class 2 serial data circuit
is low. |
| • | The above conditions are met for approximately 3 seconds. |
Action Taken When the DTC Sets
| • | The module inhibits the setting of all other class 2 DTCs. |
| • | The module uses default values for all parameters received on
the class 2 serial data circuit. |
Conditions for Clearing the DTC
| • | A U1300 will clear when a valid class 2 message is detected
on the class 2 serial data circuit or at the end of the current ignition
cycle. |
| • | A history U1300 will clear after 100 ignition switch cycles with
no repeated failure. |
Diagnostic Aids
