U0047: Vehicle Communication Bus C Performance

Definition

The OBD2 code U0047 indicates a communication issue within the vehicle's communication bus system, specifically related to the performance of the communication network

Common causes

Faulty communication module
Damaged wiring or connectors
Poor ground connections
Short circuits in the communication bus
Intermittent electrical connections
Faulty or incompatible aftermarket devices
Software issues or bugs in the control modules
Low battery voltage or power supply issues

Common misdiagnoses

Faulty Engine Control Module (ECM)
Bad Body Control Module (BCM)
Defective Transmission Control Module (TCM)
Wiring issues or shorts in the communication lines
Faulty sensors or actuators
Battery or charging system problems
Incorrectly programmed modules
Corrupted software or firmware in control modules

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 Bus C network. Look for signs of damage, corrosion, or loose connections
4. Pay special attention to the connectors on the modules that communicate over Bus C
5. Check for Short Circuits
6. Use a multimeter to check for short circuits in the wiring harness. Ensure that there are no unintended connections between wires
7. Test Modules on Bus C
8. Identify the modules that are connected to Bus C (e.g., ABS, traction control, etc.) and test their functionality. If a specific module is malfunctioning, it may cause communication issues
9. Check Power and Ground
10. Ensure that all modules on Bus C have proper power and ground connections. Use a multimeter to verify voltage and ground integrity
11. Scan for Communication Issues
12. Use a professional scan tool to check for communication between the modules on Bus C. Some tools can perform a network test to identify which module is not responding
13. Inspect the CAN Bus
14. If applicable, check the Controller Area Network (CAN) bus for proper termination and resistance. The bus should have a specific resistance (typically around 60 ohms) between the CAN high and CAN low wires
15. Update Software/Firmware
16. Check if there are any software or firmware updates available for the vehicle’s modules. Sometimes, communication issues can be resolved with an update
17. Clear Codes and Test Drive
18. After performing any repairs or adjustments, clear the trouble codes and take the vehicle for a test drive to see if the code reappears
19. Refer to the vehicle’s service manual for specific diagnostic procedures related to the communication bus and any manufacturer-specific troubleshooting steps. 1
20. Seek Professional Help
21. If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with vehicle communication systems. By following these steps, you can systematically diagnose and potentially resolve the U0047 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 associated with the Bus C network. Look for signs of damage, corrosion, or loose connections

4. Pay special attention to the connectors on the modules that communicate over Bus C

5. Check for Short Circuits

6. Use a multimeter to check for short circuits in the wiring harness. Ensure that there are no unintended connections between wires

7. Test Modules on Bus C

8. Identify the modules that are connected to Bus C (e.g., ABS, traction control, etc.) and test their functionality. If a specific module is malfunctioning, it may cause communication issues

9. Check Power and Ground

10. Ensure that all modules on Bus C have proper power and ground connections. Use a multimeter to verify voltage and ground integrity

11. Scan for Communication Issues

12. Use a professional scan tool to check for communication between the modules on Bus C. Some tools can perform a network test to identify which module is not responding

13. Inspect the CAN Bus

14. If applicable, check the Controller Area Network (CAN) bus for proper termination and resistance. The bus should have a specific resistance (typically around 60 ohms) between the CAN high and CAN low wires

15. Update Software/Firmware

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

17. Clear Codes and Test Drive

18. After performing any repairs or adjustments, clear the trouble codes and take the vehicle for a test drive to see if the code reappears

19. Refer to the vehicle’s service manual for specific diagnostic procedures related to the communication bus and any manufacturer-specific troubleshooting steps. 1

20. Seek Professional Help

21. If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with vehicle communication systems. By following these steps, you can systematically diagnose and potentially resolve the U0047 code