The P0631 code indicates that the Transmission Control Module (TCM) does not have a programmed Vehicle Identification Number (VIN) or the programmed VIN does not match the one stored in the Engine Control Module (ECM). This is typically a configuration error rather than a mechanical failure.
A replacement TCM was installed but the VIN was not flashed or programmed into the module.
A TCM from a different vehicle or a different trim level was installed, creating a VIN or configuration mismatch.
The Engine Control Module was replaced or updated, and the VIN no longer matches the existing TCM.
A software glitch or voltage spike caused the VIN data in the TCM to become corrupted.
Internal memory failure within the TCM preventing it from storing the programmed VIN.
Internal failure of the ECM preventing it from correctly broadcasting the VIN to the TCM.
No. Clearing the code does not program the VIN; the code will return immediately upon the next drive cycle until the modules are synchronized.
Not usually. In most cases, the hardware is functional, but the software configuration is missing or incorrect and needs to be programmed.
No. While the ECM is involved in the mismatch, the issue is almost always a programming omission after a part replacement rather than a hardware failure of the PCM.