U1997: Communication Network Malfunction

Definition

The OBD2 code U1997: Communication Network Malfunction indicates a failure in the communication between various control modules in the vehicle's network, which can affect their ability to exchange data properly

Common causes

Faulty wiring or connectors in the communication network
Malfunctioning control modules
Corrupted software or firmware in control modules
Poor ground connections
Interference from aftermarket devices
Damaged or shorted communication lines
Low battery voltage or power supply issues
Faulty or damaged CAN bus transceivers

Common misdiagnoses

Faulty wiring or connectors
Defective control modules
Battery or power supply issues
Software glitches or outdated firmware
Intermittent communication issues
Grounding problems
Faulty sensors or actuators
Corrupted data or configuration errors

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 associated with the communication network. Look for damaged, corroded, or loose connections
4. Pay special attention to the connectors for the modules involved in the communication network
5. Check for Short Circuits or Open Circuits
6. Use a multimeter to check for continuity in the communication lines. Look for any short circuits or open circuits that could disrupt communication
7. Verify Power and Ground
8. Ensure that all modules have the proper power supply and ground connections. A lack of power or a poor ground can cause communication issues
9. Inspect the CAN Bus
10. If your vehicle uses a Controller Area Network (CAN) bus, check the bus for proper voltage levels. The typical voltage levels should be around 2.5V for CAN High and CAN Low
11. Use an oscilloscope if available to check for proper signal waveforms on the CAN lines
12. Check for Module Malfunction
13. If a specific module is suspected to be faulty, try disconnecting it and see if the code clears. If it does, the module may need to be repaired or replaced
14. Look for Interference
15. Check for any aftermarket devices or modifications that may interfere with the vehicle's communication network, such as alarms, remote starters, or audio systems
16. Perform a Network Scan
17. Use a professional-grade scan tool to perform a network scan. This can help identify which modules are not communicating properly
18. Update Software/Firmware
19. Check if there are any software or firmware updates available for the vehicle's modules. Sometimes, updating the software can resolve communication issues
20. Clear Codes and Test Drive
21. After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns. 1
22. Refer to the vehicle's service manual for specific diagnostic procedures related to the communication network for your make and model. If the issue persists after following these steps, it may be necessary to consult a professional technician or dealership for further diagnosis and repair

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Additional Codes

2. Inspect Wiring and Connectors

3. Visually inspect the wiring and connectors associated with the communication network. Look for damaged, corroded, or loose connections

4. Pay special attention to the connectors for the modules involved in the communication network

5. Check for Short Circuits or Open Circuits

6. Use a multimeter to check for continuity in the communication lines. Look for any short circuits or open circuits that could disrupt communication

7. Verify Power and Ground

8. Ensure that all modules have the proper power supply and ground connections. A lack of power or a poor ground can cause communication issues

9. Inspect the CAN Bus

10. If your vehicle uses a Controller Area Network (CAN) bus, check the bus for proper voltage levels. The typical voltage levels should be around 2.5V for CAN High and CAN Low

11. Use an oscilloscope if available to check for proper signal waveforms on the CAN lines

12. Check for Module Malfunction

13. If a specific module is suspected to be faulty, try disconnecting it and see if the code clears. If it does, the module may need to be repaired or replaced

14. Look for Interference

15. Check for any aftermarket devices or modifications that may interfere with the vehicle's communication network, such as alarms, remote starters, or audio systems

16. Perform a Network Scan

17. Use a professional-grade scan tool to perform a network scan. This can help identify which modules are not communicating properly

18. Update Software/Firmware

19. Check if there are any software or firmware updates available for the vehicle's modules. Sometimes, updating the software can resolve communication issues

20. Clear Codes and Test Drive

21. After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns. 1

22. Refer to the vehicle's service manual for specific diagnostic procedures related to the communication network for your make and model. If the issue persists after following these steps, it may be necessary to consult a professional technician or dealership for further diagnosis and repair