U1301

DTC U1301

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 high voltage on the Class 2 serial data link for approximately three seconds, U1301 is set and 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.
* The vehicle power mode (ignition switch position) 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 current 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 upon receipt of a scan tool Clear DTCs command.

Diagnostic Aids

* This DTC cannot be retrieved with a current status. Diagnosis of a current U1301 is accomplished via the symptom, Scan Tool Does Not Communicate with a Class 2 Device. Refer to Scan Tool Does Not Communicate with Class 2 Device (LG5 Diesel) Scan Tool Does Not Communicate with Class 2 Device (LG5 Diesel)Scan Tool Does Not Communicate with Class 2 Device (L18 Gas) Scan Tool Does Not Communicate with Class 2 Device (L18 Gas)
* An intermittent condition is likely to be caused by a short to voltage on the class 2 serial data circuit. Use the Scan Tool Does Not Communicate with a Class 2 Device procedure in order to isolate an intermittent condition. Refer to Scan Tool Does Not Communicate with Class 2 Device (LG5 Diesel) Scan Tool Does Not Communicate with Class 2 Device (LG5 Diesel)Scan Tool Does Not Communicate with Class 2 Device (L18 Gas) Scan Tool Does Not Communicate with Class 2 Device (L18 Gas)