The P0631 trouble code indicates that the Vehicle Identification Number (VIN) is either not programmed into the Transmission Control Module (TCM) or it is incompatible.
VIN Not Programmed or Incompatible – TCM
Code symptoms P0631.
1. Check Engine Light (CEL) illuminated on the dashboard.
2. Transmission may not shift properly.
3. Poor acceleration or engine performance.
4. Vehicle may enter limp mode.
5. Difficulty starting the vehicle.
This code is common in brands such as:: Chevrolet, Renault, Ford, Toyota, Nissan, Mercedes Benz, Honda.
Causes of the code P0631.
1. Faulty TCM.
2. TCM programming error.
3. VIN data corruption.
4. Battery or electrical system voltage issues.
5. Aftermarket modifications affecting TCM communication.
6. Faulty wiring or connectors in the TCM circuit.
Code Solutions P0631.
1. Inspect the TCM for any visible signs of damage, such as corrosion or burnt components. Replace the TCM if necessary.
2. Ensure that the TCM is programmed with the correct VIN using manufacturer-approved programming tools.
3. Check the battery and electrical system voltage to ensure they are within normal operating range. Replace the battery or repair any electrical system issues if necessary.
4. Verify that there are no aftermarket modifications affecting TCM communication. Remove any unauthorized modifications if present.
5. Inspect the wiring and connectors associated with the TCM for damage, corrosion, or looseness. Repair or replace wiring and connectors as needed.
6. Clear the trouble codes and test drive the vehicle to see if the P0631 code returns. If it does, further diagnosis may be necessary.