Transmission Control Module (TCM) - 8HP45

U0074-DEDICATED POWERTRAIN (D-PT) CAN BUS OFF

For a complete wiring diagram Refer to the Wiring Information.

Theory of Operation

The purpose of the diagnostic is to monitor the CAN BUS, the transmitted messages on the CAN BUS and the validity of the CAN signals. Several control units are connected to the CAN BUS which send their messages cyclically in a defined time window. The messages contain multiple signals representing vehicle information.

- When Monitored:
Continuously with the ignition on and voltage within a valid range.

No failure in CAN BUS monitoring.

No failure in CAN BUS or message monitoring.

- Set Condition:
The controller detects an open, short to ground or short to voltage on the CAN C BUS circuit.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. 8HP45 Pre-Diagnostic Troubleshooting Procedure

VERIFY DTC IS ACTIVE

NOTE: For vehicle communication problems, use the scan tool to refer to the Network Review Screen. The screen depicts a high level view of the vehicle network. Fault and problem areas appear in red. Selecting any of the network components allows access to the source of the problem.

1. Turn the ignition ON.
2. With the scan tool, read active DTCs.

Is this DTC active?

Yes

- the U0002-CAN C BUS Off Performance diagnostic procedure. U0002

No

- Perform the Stored Lost Communication DTCs diagnostic procedure. Stored Lost Communication DTCs