U1917: U1917: "Module Communication Failure

Definition

The OBD2 code U1917 indicates a "Module Communication Failure," meaning there is a problem with communication between the vehicle's control modules, often due to a fault in the wiring, connectors, or the modules themselves

Common causes

Faulty wiring or connectors
Failed or malfunctioning control module
Poor ground connections
Corrupted software or firmware in the module
Interference from aftermarket devices
Low battery voltage or weak battery
Communication network issues (e.g., CAN bus problems)
Damaged or corroded pins in connectors
Faulty or damaged sensors related to the module
Incompatible or missing modules in the network

Common misdiagnoses

Faulty wiring or connectors
Defective control module
Software issues or updates needed
Power supply problems
Grounding issues
Intermittent communication issues
Other communication protocol failures

Troubleshooting steps

1. Check for Other 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 affected module(s). Look for signs of damage, corrosion, or loose connections
4. Pay special attention to the wiring harnesses that connect the modules, as these can be prone to wear and tear
5. Check Power and Ground
6. Ensure that the affected module has a proper power supply and ground connection. Use a multimeter to check for voltage at the module's connector
7. If the module is not receiving power, trace the wiring back to the fuse box and check for blown fuses or damaged wires
8. Test the Module
9. If possible, test the affected module by swapping it with a known good module (if available) to see if the problem persists
10. Some modules may have built-in self-diagnostic capabilities that can provide additional information
11. Check for Communication
12. Use a scan tool to check if the affected module is communicating with other modules. If it is not, there may be a fault within the module itself or the communication network
13. You can also use a scope or a scan tool to monitor the data bus for activity
14. Inspect the CAN Bus
15. If your vehicle uses a Controller Area Network (CAN) bus, check for issues with the bus itself. Look for short circuits, open circuits, or interference that could disrupt communication
16. Use a CAN bus tester if available to check for proper signal levels and integrity
17. Check for Software Updates
18. Sometimes, communication issues can be resolved with a software update. Check with the vehicle manufacturer for any available updates for the affected module(s)
19. Clear Codes and Test Drive
20. After performing any repairs or adjustments, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns
21. Consult Technical Service Bulletins (TSBs)
22. Check for any TSBs related to the specific make and model of your vehicle. Manufacturers may have issued guidance on common communication issues
23. Seek Professional Help
24. If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with your vehicle's specific systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1917 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Other Codes

2. Inspect Wiring and Connectors

3. Visually inspect the wiring and connectors associated with the affected module(s). Look for signs of damage, corrosion, or loose connections

4. Pay special attention to the wiring harnesses that connect the modules, as these can be prone to wear and tear

5. Check Power and Ground

6. Ensure that the affected module has a proper power supply and ground connection. Use a multimeter to check for voltage at the module's connector

7. If the module is not receiving power, trace the wiring back to the fuse box and check for blown fuses or damaged wires

8. Test the Module

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

10. Some modules may have built-in self-diagnostic capabilities that can provide additional information

11. Check for Communication

12. Use a scan tool to check if the affected module is communicating with other modules. If it is not, there may be a fault within the module itself or the communication network

13. You can also use a scope or a scan tool to monitor the data bus for activity

14. Inspect the CAN Bus

15. If your vehicle uses a Controller Area Network (CAN) bus, check for issues with the bus itself. Look for short circuits, open circuits, or interference that could disrupt communication

16. Use a CAN bus tester if available to check for proper signal levels and integrity

17. Check for Software Updates

18. Sometimes, communication issues can be resolved with a software update. Check with the vehicle manufacturer for any available updates for the affected module(s)

19. Clear Codes and Test Drive

20. After performing any repairs or adjustments, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

21. Consult Technical Service Bulletins (TSBs)

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

23. Seek Professional Help