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 about once every two
seconds. When the module detects no messages and a low voltage on the
class 2 serial data circuit for approximately three seconds, U1300
is set and the setting of all other class 2 serial communication
DTCs is inhibited.
Conditions for Running the DTC
| • | The following diagnostic trouble codes do not have a current status: |
| • | The vehicle power mode (ignition switch position) 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 current 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 upon receipt of a scan tool Clear DTCs
command. |
Diagnostic Aids
