U1795 – Transmission Control Module Communication Error

The ODBII code U1795 indicates a communication error between the Transmission Control Module (TCM) and other control modules in the vehicle, suggesting a possible issue with wiring, connectors, or the TCM itself.

The severity of ODBII code U1795 is moderate to severe.

Common Causes For: U1794 SCP (J1850) Lack of Acknowledgment for Mirrors

• Faulty Transmission Control Module (TCM)
• Damaged wiring or connectors
• Poor ground connections
• Faulty Engine Control Module (ECM)
• Software issues or programming errors
• Corroded or loose connectors
• Electrical interference
• Low battery voltage or weak battery
• Faulty CAN bus communication
• Malfunctioning sensors related to transmission

Common misdiagnosis for U1795 U1795: Transmission Control Module Communication Error

• Faulty Transmission Control Module (TCM)
• Wiring or connector issues
• Faulty Engine Control Module (ECM)
• Low transmission fluid levels
• Faulty sensors (e.g., speed sensors)
• Software issues or updates needed
• Battery or charging system problems
• Grounding issues
• Faulty transmission solenoids
• Corrupted data communication lines

Common Troubleshooting Steps

The OBD-II code U1795 indicates a communication error 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, related codes can provide more context for the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring harness and connectors associated with the TCM. Look for signs of damage, corrosion, or loose connections.
• Ensure that all connectors are securely plugged in and that there are no bent pins.
• Check Power and Ground:
• Verify that the TCM is receiving the correct voltage and ground. Use a multimeter to check the power supply and ground connections to the TCM.
• If there is no power or ground, trace the wiring back to the source to identify any breaks or shorts.
• Test the TCM:
• If the wiring and connections are intact, the TCM itself may be faulty. Testing the TCM may require specialized equipment or a professional diagnostic tool.
• In some cases, reprogramming or updating the TCM software may resolve communication issues.
• Inspect the CAN Bus:
• The TCM communicates with other modules via the Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring or connections.
• Use a scan tool to monitor the CAN bus for any irregularities or communication failures.
• Check for Interference:
• Look for any aftermarket devices or modifications that may interfere with the vehicle’s communication network. This includes alarm systems, stereo systems, or other electronic devices.
• Clear Codes and Test Drive:
• After addressing any identified issues, 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 U1795 code for your specific vehicle make and model. Manufacturers may have issued guidance on common issues and fixes.
• 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 and repair. By following these steps, you can systematically identify and resolve the communication error associated with the U1795 code.