U1937 – Module Communication Failure

The ODBII code U1937 indicates a “Module Communication Failure,” meaning there is a problem with communication between vehicle modules, often due to a fault in the wiring, connectors, or the modules themselves.

The severity of ODBII code U1937 is generally considered moderate to severe.

Common Causes For: U1936 U1936: “Module Communication Failure”

• Faulty wiring or connectors
• Failed or malfunctioning control module
• Corrupted software or firmware in the module
• Poor ground connections
• Interference from aftermarket devices
• Low battery voltage or power supply issues
• Communication network issues (e.g., CAN bus problems)

Common misdiagnosis for U1937 U1937: “Module Communication Failure”

• Faulty wiring or connectors
• Defective control module
• Software issues or updates needed
• Battery or power supply problems
• Grounding issues
• Intermittent communication issues
• Other module failures in the network

Common Troubleshooting Steps

The OBD-II code U1937 indicates a “Module Communication Failure,” which typically means 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 other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the affected module. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the ground connections, as poor grounding can lead to communication issues.
• Check the Affected Module:
• Identify which module is reporting the U1937 code. This could be a specific control module (e.g., ABS, BCM, etc.).
• If possible, test the module by checking its power and ground supply. Ensure that it is receiving the correct voltage.
• Perform a Network Test:
• Use a scan tool capable of performing a network test to check the communication between modules. This can help identify if the issue is isolated to one module or if it affects multiple modules.
• Inspect the CAN Bus:
• If your vehicle uses a Controller Area Network (CAN) bus, check for issues with the bus itself. Look for short circuits, open circuits, or any other faults in the wiring.
• You can use an oscilloscope to check the signal integrity on the CAN bus lines.
• Check for Software Updates:
• Sometimes, communication issues can be resolved with a software update. Check with the manufacturer for any available updates for the affected module.
• Reset the Modules:
• Clear the trouble codes using a scan tool and see if the code returns. Sometimes, a temporary glitch can cause communication failures.
• Replace the Module:
• If all other troubleshooting steps fail and the module is determined to be faulty, consider replacing the affected control module.
• Consult Technical Service Bulletins (TSBs):
• Check for any TSBs related to the U1937 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues.
• Seek Professional Help:
• If you are unable to resolve the issue, consider seeking help from a qualified technician or automotive professional who has experience with your vehicle’s make and model. By following these steps, you should be able to diagnose and potentially resolve the U1937 code. Always refer to the vehicle’s service manual for specific procedures and specifications.