U1738 – Control Module Communication Failure

The ODBII code U1738 indicates a communication failure between control modules in a vehicle, suggesting that one or more modules are not properly communicating with each other.

The severity of ODBII code U1738 is moderate.

Common Causes For: U1737 U1737: “Module Communication Failure”

• Faulty control module
• Damaged wiring or connectors
• Poor ground connections
• Corroded terminals
• Communication network issues (e.g., CAN bus problems)
• Software glitches or outdated firmware
• Intermittent electrical issues
• Battery or power supply problems

Common misdiagnosis for U1738 U1738: Control Module Communication Failure

• Faulty control module
• Wiring issues
• Poor ground connections
• Corrupted software or firmware
• Faulty sensors
• Communication network issues
• Battery or power supply problems
• Intermittent connection issues

Common Troubleshooting Steps

The OBD-II code U1738 indicates a communication failure between control modules in a vehicle. This can be caused by various issues, including wiring problems, faulty modules, or issues with the vehicle’s network. Here are some common troubleshooting steps to diagnose and resolve the U1738 code:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context about the issue.
• Inspect Wiring and Connectors: **Visual Inspection: Look for damaged, frayed, or corroded wiring and connectors related to the control modules.
• **Connector Integrity: Ensure that all connectors are securely attached and free of corrosion or dirt.
• Check Power and Ground: Verify that the affected control module has the proper power supply and ground. Use a multimeter to check voltage and ground continuity.
• Test Control Modules: If possible, test the affected control module for proper operation. This may involve using specialized diagnostic tools or swapping with a known good module.
• Inspect the CAN Bus: The Controller Area Network (CAN) bus is responsible for communication between modules. Check for:
• Short circuits or open circuits in the CAN bus wiring.
• Termination resistors at the ends of the CAN bus; ensure they are present and functioning.
• Check for Interference: Look for any aftermarket devices or modifications that may interfere with the vehicle’s communication network.
• Perform a Network Test: Use a scan tool capable of performing a network test to check for communication between modules. This can help identify which module is not communicating.
• Clear Codes and Test Drive: After performing checks and repairs, clear the trouble codes 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 U1738 code and the control modules involved.
• Seek Professional Help: If the issue persists after performing the above steps, consider seeking assistance from a qualified technician or automotive specialist who has experience with your vehicle’s make and model. By following these steps, you can systematically diagnose and address the underlying issues causing the U1738 code.