U1301

DTC U1300, U1301, or U1305

Circuit Description

Each control module connected to the class 2 serial data circuit monitors the voltage on the circuit. If a control module detects the class 2 serial data circuit is open or shorted for 3 seconds, all other class 2 serial communication DTCs are inhibited and DTC U1300, U1301, or U1305 will set.

DTC Descriptors

This diagnostic procedure supports the following DTCs.

- DTC U1300 Class 2 Data Link Low.
- DTC U1301 Class 2 Data Link High.
- DTC U1305 Class 2 Data Link Low or High.

Conditions for Running the DTC

- Voltage supplied to the module is in the normal operating voltage range.
- The vehicle power mode 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 always low or always high.
- The above conditions are met for 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 DTC clears when the malfunction is no longer present, or when the ignition is cycled.
- A history DTC clears when the ignition has been cycled 100 times, without a repeat of the malfunction.

Diagnostic Aids

- DTCs U1300, U1301, and U1305 cannot be retrieved while the condition is present. Diagnosis of these DTCs 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 Devise.
- An intermittent condition is likely to be caused by a short or an open 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 Devise.