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 high voltage on the class 2
serial data link for approximately 3 seconds, U1301 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 class 2 messages are detected on the class 2
serial data circuit. |
| • | The voltage level detected on the class 2 serial data circuit
is high. |
| • | 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 U1301 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 U1301 will clear after 100 ignition cycles with no repeated
failures. |
Diagnostic Aids
