U1744: U1744: Transmission Control Module Communication Error

Definition

The OBD2 code U1744 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

Common causes

Faulty Transmission Control Module (TCM)
Damaged wiring or connectors
Poor electrical connections
Faulty Engine Control Module (ECM)
Software issues or bugs
Low battery voltage
Corroded terminals
Faulty CAN bus communication
Grounding issues
Intermittent electrical faults

Common misdiagnoses

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Software issues or outdated firmware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
Corroded or loose electrical connections

Troubleshooting steps

1. 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
2. Inspect Wiring and Connectors
3. Visually inspect the wiring harness and connectors related to the TCM. Look for signs of damage, corrosion, or loose connections
4. Ensure that all connectors are securely plugged in and that there are no bent pins
5. Check Power and Ground
6. Verify that the TCM is receiving the correct power supply. Use a multimeter to check the voltage at the TCM connector
7. Check the ground connections to ensure they are secure and free of corrosion
8. Test the TCM
9. If possible, test the TCM for proper operation. This may involve using specialized diagnostic equipment or swapping in a known good TCM if available
10. Inspect the CAN Bus
11. The TCM communicates over the Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts or opens
12. Use a scan tool to monitor the CAN bus for communication errors or interruptions
13. Check for Software Updates
14. Sometimes, a software update for the TCM or other modules can resolve communication issues. Check with the manufacturer for any available updates
15. Clear Codes and Test Drive
16. After performing any repairs or inspections, clear the trouble codes and take the vehicle for a test drive to see if the code returns
17. Refer to the vehicle's service manual for specific diagnostic procedures related to the TCM and communication errors
18. Professional Diagnosis
19. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing transmission control issues. By following these steps, you can systematically identify and address the root cause of the U1744 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Additional Codes

2. Inspect Wiring and Connectors

3. Visually inspect the wiring harness and connectors related to the TCM. Look for signs of damage, corrosion, or loose connections

4. Ensure that all connectors are securely plugged in and that there are no bent pins

5. Check Power and Ground

6. Verify that the TCM is receiving the correct power supply. Use a multimeter to check the voltage at the TCM connector

7. Check the ground connections to ensure they are secure and free of corrosion

8. Test the TCM

9. If possible, test the TCM for proper operation. This may involve using specialized diagnostic equipment or swapping in a known good TCM if available

10. Inspect the CAN Bus

11. The TCM communicates over the Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts or opens

12. Use a scan tool to monitor the CAN bus for communication errors or interruptions

13. Check for Software Updates

14. Sometimes, a software update for the TCM or other modules can resolve communication issues. Check with the manufacturer for any available updates

15. Clear Codes and Test Drive

16. After performing any repairs or inspections, clear the trouble codes and take the vehicle for a test drive to see if the code returns

17. Refer to the vehicle's service manual for specific diagnostic procedures related to the TCM and communication errors

18. Professional Diagnosis

19. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing transmission control issues. By following these steps, you can systematically identify and address the root cause of the U1744 code