U1747 – Transmission Control Module Communication Error
The ODBII code U1747 indicates a communication error between the Transmission Control Module (TCM) and other control modules in the vehicle, suggesting a possible issue with wiring, connectors, or the TCM itself.
The severity of ODBII code U1747 is moderate to severe.
Common Causes For: U1746 U1746: Transmission Control Module Communication Error
- Faulty Transmission Control Module (TCM)
- Damaged wiring or connectors
- Poor electrical connections
- Faulty Engine Control Module (ECM)
- Software issues or programming errors
- Low battery voltage or electrical system issues
- Corroded or loose ground connections
- Faulty CAN bus communication
- Intermittent faults in the transmission system
Common misdiagnosis for U1747 U1747: Transmission Control Module Communication Error
- Faulty Transmission Control Module (TCM)
- Wiring issues or damaged connectors
- Faulty Engine Control Module (ECM)
- Low transmission fluid levels
- Faulty sensors (e.g., speed sensors)
- Software issues or outdated firmware
- Battery or charging system problems
- Grounding issues
- Faulty transmission solenoids
- Corrupted data in the vehicle’s communication network
Common Troubleshooting Steps
The OBD-II code U1747 indicates a communication error between the Transmission Control Module (TCM) and other modules in the vehicle’s network. Here are some common troubleshooting steps to diagnose and resolve this issue:
- Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue.
- Inspect Wiring and Connectors:
- Visually inspect the wiring harness and connectors related to the TCM for any signs of damage, corrosion, or loose connections.
- Pay special attention to the connectors at the TCM and any related modules.
- Check Power and Ground:
- Verify that the TCM is receiving the correct voltage and ground. Use a multimeter to check the power supply and ground connections to the TCM.
- Ensure that the battery is in good condition and fully charged.
- Test the TCM:
- If possible, perform a bench test on the TCM to ensure it is functioning correctly. This may require specialized equipment or tools.
- If the TCM is suspected to be faulty, consider replacing it with a known good unit.
- Inspect the CAN Bus:
- The TCM communicates with other modules via the Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts, opens, or interference.
- Use a scan tool to monitor the CAN bus for proper communication between modules.
- Check for Software Updates:
- Sometimes, communication issues can be resolved with a software update. Check with the vehicle manufacturer for any available updates for the TCM or other related modules.
- Clear Codes and Test Drive:
- After performing any repairs or inspections, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns.
- Consult Service Manual:
- Refer to the vehicle’s service manual for specific diagnostic procedures related to the TCM and communication errors. This may provide additional insights or steps tailored to your vehicle model.
- Seek Professional Help:
- If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with transmission control systems and can perform more advanced diagnostics. By following these steps, you should be able to identify and resolve the communication error associated with the U1747 code.