U1773 – Transmission Control Module Communication Error
The ODBII code U1773 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 U1773 is moderate to severe.
Common Causes For: U1772 U1772: “Control Module Communication Failure”
- 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 U1773 U1773: Transmission Control Module Communication Error
- Faulty Transmission Control Module (TCM)
- Wiring or connector issues
- Faulty Engine Control Module (ECM)
- Low transmission fluid levels
- Faulty sensors (e.g., speed sensors)
- Software issues or updates needed
- Battery or charging system problems
- Grounding issues
- Faulty transmission solenoids
- Corrupted data communication lines
Common Troubleshooting Steps
The OBD-II code U1773 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 and connectors related to the TCM. Look for signs of damage, corrosion, or loose connections.
- Pay special attention to the wiring harness that connects the TCM to the vehicle’s main harness.
- Check Power and Ground:
- Verify that the TCM is receiving the correct power supply. Use a multimeter to check the voltage at the TCM connector.
- Ensure that the ground connections are secure and free of corrosion.
- Test the TCM:
- If possible, test the TCM for proper operation. This may involve using specialized diagnostic equipment or swapping in a known good TCM if available.
- Inspect Other Modules:
- Check other modules in the vehicle that communicate with the TCM, such as the Engine Control Module (ECM) or Body Control Module (BCM). Ensure they are functioning correctly and that their connections are secure.
- Check for Short Circuits:
- Use a multimeter to check for short circuits in the wiring harness. A short can cause communication errors.
- Update Software/Firmware:
- In some cases, a software update for the TCM or other related modules may be necessary. Check with the manufacturer for any available updates.
- Clear Codes and Test Drive:
- After performing any repairs or checks, clear the trouble codes and take the vehicle for a test drive to see if the code returns.
- Consult Technical Service Bulletins (TSBs):
- Look for any TSBs related to the U1773 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues.
- Seek Professional Help:
- If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or dealership for further diagnosis. By following these steps, you can systematically identify and resolve the communication error associated with the U1773 code.