U1948 – Module Communication Failure

The ODBII code U1948: Module Communication Failure indicates that there is a communication issue between the vehicle’s control modules, preventing them from exchanging data properly.

The severity of ODBII code **U1948: Module Communication Failure** is generally considered moderate to severe.

Common Causes For: U1933: Module Communication Fault

• 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 weak battery
• Communication network issues (e.g., CAN bus problems)
• Damaged or corroded pins in connectors

Common misdiagnosis for U1948: Module Communication Failure

• Faulty wiring or connectors
• Defective control module
• Low battery voltage
• Intermittent communication issues
• Software glitches or outdated firmware
• Incorrectly configured or programmed modules
• Grounding issues
• Faulty sensors or actuators
• Corrupted data or signals
• Environmental interference (e.g., electromagnetic interference)

Common Troubleshooting Steps

The OBD-II code **U1948: Module Communication Failure** indicates that there is a communication issue between the vehicle’s control modules. This can be caused by various factors, including wiring issues, faulty modules, or problems with the vehicle’s network. 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. Other codes may provide more context about the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors related to the affected module. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the wiring harnesses that connect the modules, as these can be prone to wear and tear.
• Check Power and Ground:
• Verify that the affected module is receiving proper power and ground. Use a multimeter to check voltage and ground continuity at the module’s connector.
• Test the Affected Module:
• If possible, test the affected module to ensure it is functioning correctly. This may involve swapping it with a known good module or using a diagnostic tool to perform module tests.
• Inspect the CAN Bus:
• The communication between modules often occurs over the Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts or opens.
• Use an oscilloscope or a CAN bus diagnostic tool to monitor the bus for proper communication signals.
• Check for Interference:
• Look for any aftermarket devices or modifications that may interfere with the vehicle’s communication network. This includes alarms, remote starters, or other electronic accessories.
• Reset the Modules:
• Clear the trouble codes using an OBD-II scanner and see if the code returns. Sometimes, a temporary glitch can cause communication failures.
• Update Software/Firmware:
• Check if there are any software or firmware updates available for the vehicle’s modules. Sometimes, manufacturers release updates to fix communication issues.
• Consult Technical Service Bulletins (TSBs):
• Look for any TSBs related to the U1948 code for your specific vehicle make and model. Manufacturers may have identified common issues and provided solutions.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have specialized diagnostic tools and experience with your vehicle. By following these steps, you can systematically diagnose and potentially resolve the U1948 code. Always refer to the vehicle’s service manual for specific procedures and specifications related to your vehicle.