U1684 – refers to a communication issue between the Body Control Module (BCM) and the Instrument Panel Cluster (IPC).

The ODBII code U1684 indicates a communication issue between the Body Control Module (BCM) and the Instrument Panel Cluster (IPC), suggesting a failure in data exchange between these two components.

The severity of ODBII code U1684 is moderate.

Common Causes For: U1683 Invalid Data Received from Vehicle Control Module.

• Faulty Body Control Module (BCM)
• Faulty Instrument Panel Cluster (IPC)
• Damaged wiring or connectors between BCM and IPC
• Corrosion at connectors
• Poor ground connections
• Software issues or programming errors
• Intermittent electrical connections
• Short circuits in the communication lines

Common misdiagnosis for U1684 refers to a communication issue between the Body Control Module (BCM) and the Instrument Panel Cluster (IPC).

• Faulty Body Control Module (BCM)
• Faulty Instrument Panel Cluster (IPC)
• Wiring issues or shorts in communication lines
• Corrupted software or firmware in BCM or IPC
• Battery or power supply issues
• Grounding problems
• Faulty connectors or terminals
• Other communication network issues (e.g., CAN bus problems)

Common Troubleshooting Steps

When dealing with OBD-II code U1684, which indicates a communication issue between the Body Control Module (BCM) and the Instrument Panel Cluster (IPC), you can follow these common troubleshooting steps:

• Check for Additional Codes: Before diving into specific troubleshooting, check for any other diagnostic trouble codes (DTCs) that may provide more context or indicate related issues.
• Inspect Wiring and Connectors:
• Visually inspect the wiring harness and connectors between the BCM and IPC for any signs of damage, corrosion, or loose connections.
• Ensure that all connectors are securely plugged in and that there are no bent pins.
• Test Power and Ground:
• Verify that the BCM and IPC are receiving the correct power and ground signals. Use a multimeter to check voltage levels at the connectors.
• Check for any blown fuses related to the BCM or IPC.
• Check for Short Circuits:
• Use a multimeter to check for short circuits in the wiring between the BCM and IPC. This includes checking for continuity where there shouldn’t be any.
• Inspect the BCM and IPC:
• If the wiring and connections are intact, consider testing the BCM and IPC for proper operation. This may involve using a scan tool to check for communication errors or performing specific tests as outlined in the vehicle’s service manual.
• Perform a Network Test:
• If available, use a scan tool to perform a network test to see if other modules are communicating properly. This can help identify if the issue is isolated to the BCM and IPC or if it’s part of a larger communication problem.
• Check for Software Updates:
• Sometimes, communication issues can be resolved with a software update. Check with the manufacturer for any available updates for the BCM or IPC.
• Clear Codes and Test Drive:
• After performing the above checks and repairs, clear the codes using a scan tool and take the vehicle for a test drive to see if the code reappears.
• Consult Service Manual:
• If the issue persists, consult the vehicle’s service manual for specific diagnostic procedures related to the BCM and IPC communication.
• Seek Professional Help:
• If you are unable to resolve the issue after following these steps, it may be necessary to seek assistance from a professional mechanic or dealership with experience in diagnosing and repairing communication issues in automotive systems. By following these steps, you can systematically identify and address the root cause of the U1684 code.