U1546 – Control Module Communication Failure

The ODBII code U1546 indicates a “Control Module Communication Failure,” meaning there is a problem with communication between the vehicle’s control modules, which can affect various systems and functions.

Moderate to Severe.

Common Causes For: U1545 U1545: “BCM Communication Failure”

• Faulty control module
• Poor electrical connections
• Damaged wiring harness
• Corroded connectors
• Software issues or bugs
• Low battery voltage
• Interference from aftermarket devices
• Faulty CAN bus communication
• Grounding issues

Common misdiagnosis for U1546 U1546: “Control Module Communication Failure”

• Faulty control module
• Wiring issues
• Poor ground connections
• Corrupted software/firmware
• Faulty sensors
• Battery or power supply problems
• Intermittent connection issues
• Communication network faults (e.g., CAN bus issues)

Common Troubleshooting Steps

The OBD-II code U1546 indicates a “Control Module Communication Failure.” This code typically suggests that there is a problem with communication between the vehicle’s control modules. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Other Codes: Use an OBD-II scanner to check for any additional trouble codes. Sometimes, other codes can provide context or lead to the root cause of the communication failure.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the control modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the wiring harnesses that connect the affected modules.
• Check Power and Ground:
• Ensure that the control modules have proper power and ground connections. Use a multimeter to check for voltage at the module connectors.
• Verify that the ground connections are clean and secure.
• Test the Control Modules:
• If possible, test the affected control modules individually to ensure they are functioning correctly. This may involve swapping with a known good module if available.
• Some modules may require specific diagnostic tools or procedures to test.
• Inspect the CAN Bus:
• The communication between control modules often occurs over a Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts or opens.
• Use a CAN bus scanner to monitor the communication and check for any anomalies.
• Check for Software Updates:
• Sometimes, a software update from the manufacturer can resolve communication issues. Check if there are any available updates for the control modules.
• Clear Codes and Test Drive:
• After performing any repairs or inspections, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Consult Service Manual:
• Refer to the vehicle’s service manual for specific diagnostic procedures related to the U1546 code. This may provide additional insights or steps tailored to your vehicle’s make and model.
• Seek Professional Help:
• If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or dealership for further diagnosis. They may have specialized tools and knowledge to address complex communication issues. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1546 code.