U1875 – TCM Communication Failure

The ODBII code U1875: TCM Communication Failure indicates a loss of communication between the vehicle’s Transmission Control Module (TCM) and other control modules, which can affect transmission performance and functionality.

The severity of ODBII code U1875: TCM Communication Failure is typically considered moderate to severe.

Common Causes For: U1874 refers to a communication issue between the transmission control module (TCM) and other control modules in the vehicle.

• Faulty Transmission Control Module (TCM)
• Damaged wiring or connectors in the TCM circuit
• Poor ground connection
• Failed or malfunctioning Engine Control Module (ECM)
• Communication network issues (e.g., CAN bus problems)
• Corroded or loose connectors
• Software issues or outdated firmware
• Electrical interference from other components

Common misdiagnosis for U1875 U1875: TCM Communication Failure

• Transmission Control Module (TCM) failure
• Engine Control Module (ECM) issues
• Wiring harness problems
• Faulty connectors or terminals
• Powertrain Control Module (PCM) issues
• Sensor malfunctions
• Battery or charging system problems
• Grounding issues

Common Troubleshooting Steps

The OBD-II code U1875 indicates a communication failure between the Transmission Control Module (TCM) and other modules in 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. Sometimes, other codes can provide context or indicate related issues.
• Inspect Wiring and Connectors:
• Visually inspect the wiring harness and connectors associated with the TCM. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors at the TCM and any junction points in the wiring.
• Check Power and Ground:
• Verify that the TCM is receiving the correct power supply. Use a multimeter to check voltage at the TCM connector.
• Ensure that the ground connections are secure and free of corrosion.
• Test the TCM:
• If possible, test the TCM for proper operation. This may involve using a scan tool to check for communication with the TCM or performing specific tests as outlined in the vehicle’s service manual.
• Inspect the CAN Bus:
• The TCM communicates over the Controller Area Network (CAN) bus. Check for issues with the CAN bus wiring, such as shorts, opens, or interference.
• Use a scan tool to monitor the CAN bus for proper communication between modules.
• Check for Software Updates:
• Sometimes, a software update for the TCM or other modules can resolve communication issues. Check with the manufacturer for any available updates.
• Clear Codes and Test Drive:
• After performing any repairs or inspections, clear the trouble codes and take the vehicle for a test drive to see if the code reappears.
• Consult Service Manual:
• Refer to the vehicle’s service manual for specific diagnostic procedures related to the TCM and communication issues. This may provide additional insights or steps tailored to your vehicle.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have specialized tools and knowledge to diagnose complex communication issues. By following these steps, you can systematically identify and address the cause of the U1875 code.