U1964: Module Communication Failure

Definition

The OBD2 code U1964 indicates a communication failure between modules in the vehicle's network, suggesting that one or more control modules are not communicating properly with each other

Common causes

Faulty wiring or connectors
Malfunctioning control module
Poor ground connections
Interference from aftermarket devices
Software issues or bugs
Low battery voltage
Corroded terminals
Communication network issues (e.g., CAN bus problems)

Common misdiagnoses

Faulty wiring or connectors
Defective control module
Software issues or updates needed
Battery or power supply problems
Grounding issues
Intermittent communication issues
Other module failures (e.g., ABS, BCM)

Troubleshooting steps

1. Check for Other Codes

Use an OBD-II scanner to check for any additional trouble codes. Sometimes, multiple codes can provide more context about the issue
2. Inspect the Wiring and Connectors
3. Examine the wiring harnesses and connectors associated with the affected module. Look for signs of damage, corrosion, or loose connections
4. Pay special attention to ground connections, as poor grounding can lead to communication issues
5. Verify Power Supply
6. Ensure that the module in question is receiving the proper voltage and ground. Use a multimeter to check the power supply to the module
7. Check the vehicle’s fuses related to the module for any blown fuses
8. Check for Module Functionality
9. If possible, test the affected module by swapping it with a known good module (if applicable) to see if the problem persists
10. Some modules may have self-diagnostic capabilities; check if the module can perform self-tests
11. Inspect the CAN Bus
12. If the vehicle uses a Controller Area Network (CAN) bus, check for communication issues on the bus. Use a scan tool that can monitor CAN bus traffic
13. Look for any short circuits or open circuits in the CAN wiring
14. Update Software/Firmware
15. Check if there are any software or firmware updates available for the vehicle’s modules. Sometimes, communication issues can be resolved with an update
16. Clear Codes and Test Drive
17. After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code reappears
18. Consult Technical Service Bulletins (TSBs)
19. Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common communication issues
20. Professional Diagnosis
21. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with advanced diagnostic tools. By following these steps, you can systematically identify and resolve the underlying cause of the U1964 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Other Codes

2. Inspect the Wiring and Connectors

3. Examine the wiring harnesses and connectors associated with the affected module. Look for signs of damage, corrosion, or loose connections

4. Pay special attention to ground connections, as poor grounding can lead to communication issues

5. Verify Power Supply

6. Ensure that the module in question is receiving the proper voltage and ground. Use a multimeter to check the power supply to the module

7. Check the vehicle’s fuses related to the module for any blown fuses

8. Check for Module Functionality

9. If possible, test the affected module by swapping it with a known good module (if applicable) to see if the problem persists

10. Some modules may have self-diagnostic capabilities; check if the module can perform self-tests

11. Inspect the CAN Bus

12. If the vehicle uses a Controller Area Network (CAN) bus, check for communication issues on the bus. Use a scan tool that can monitor CAN bus traffic

13. Look for any short circuits or open circuits in the CAN wiring

14. Update Software/Firmware

15. Check if there are any software or firmware updates available for the vehicle’s modules. Sometimes, communication issues can be resolved with an update

16. Clear Codes and Test Drive

17. After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code reappears

18. Consult Technical Service Bulletins (TSBs)

19. Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common communication issues

20. Professional Diagnosis

21. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with advanced diagnostic tools. By following these steps, you can systematically identify and resolve the underlying cause of the U1964 code