U1773: U1773: Transmission Control Module Communication Error

Definition

The OBD2 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

Common causes

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 misdiagnoses

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

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 and connectors related to the TCM. Look for signs of damage, corrosion, or loose connections
4. Pay special attention to the wiring harness that connects the TCM to the vehicle's main harness
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. Ensure that the ground connections 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 Other Modules
11. 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
12. Check for Short Circuits
13. Use a multimeter to check for short circuits in the wiring harness. A short can cause communication errors
14. Update Software/Firmware
15. In some cases, a software update for the TCM or other related modules may be necessary. Check with the manufacturer for any available updates
16. Clear Codes and Test Drive
17. After performing any repairs or checks, clear the trouble codes and take the vehicle for a test drive to see if the code returns
18. Consult Technical Service Bulletins (TSBs)
19. Look for any TSBs related to the U1773 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues
20. Seek Professional Help
21. 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

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Additional Codes

2. Inspect Wiring and Connectors

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

4. Pay special attention to the wiring harness that connects the TCM to the vehicle's main harness

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. Ensure that the ground connections 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 Other Modules

11. 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

12. Check for Short Circuits

13. Use a multimeter to check for short circuits in the wiring harness. A short can cause communication errors

14. Update Software/Firmware

15. In some cases, a software update for the TCM or other related modules may be necessary. Check with the manufacturer for any available updates

16. Clear Codes and Test Drive

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

18. Consult Technical Service Bulletins (TSBs)

19. Look for any TSBs related to the U1773 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues

20. Seek Professional Help

21. 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