U1502 – Control Module Communication Fault

The ODBII code U1502 indicates a “Control Module Communication Fault,” meaning there is a problem with communication between the vehicle’s control modules, which may affect their ability to share data and function properly.

Moderate to Severe.

Common Causes For: U1501 refers to a communication issue between the engine control module (ECM) and the transmission control module (TCM).

• Faulty control module
• Damaged wiring or connectors
• Poor ground connections
• Corroded terminals
• Software issues or bugs
• Communication network issues (e.g., CAN bus problems)
• Low battery voltage
• Intermittent electrical connections
• Faulty sensors or actuators
• Aftermarket modifications or installations affecting communication

Common misdiagnosis for U1502 U1502: “Control Module Communication Fault”

• Faulty control module
• Wiring issues or shorts
• Poor ground connections
• Corroded connectors
• Faulty sensors
• Battery or charging system problems
• Software glitches or outdated firmware
• Intermittent communication issues
• Faulty CAN bus or communication lines
• Other unrelated module failures

Common Troubleshooting Steps

The OBD-II code U1502 indicates a “Control Module Communication Fault.” 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 Additional 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 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 voltage and ground continuity.
• If there are issues with power or ground, repair the wiring as necessary.
• Test Control Modules:
• If you suspect a specific control module is faulty, you may need to test or replace it. This can involve swapping it with a known good module if available.
• Some modules may require reprogramming or calibration after replacement.
• Inspect the CAN Bus:
• The Controller Area Network (CAN) bus is responsible for communication between modules. Check for any faults in the CAN bus wiring.
• Use an oscilloscope or a CAN bus diagnostic tool to monitor the communication signals on the bus.
• Check for Interference:
• Look for any aftermarket devices or modifications that may interfere with the vehicle’s communication systems. This includes alarms, stereo systems, or other electronic devices.
• Clear Codes and Test Drive:
• After performing any repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Consult Technical Service Bulletins (TSBs):
• Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to communication faults.
• 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 steps, you can systematically diagnose and potentially resolve the U1502 code.