Circuit/System Verification

Ignition ON.
Verify that no other DTCs are set except for C1251 is set.
- If any other DTCs are set
  Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- If no other DTCs are set
Replace the K71 Transmission Control Module.
Verify that DTC C1251 does not set while operating the vehicle within the Conditions for Running the DTC.
- If the DTC sets
  Replace the K17 Electronic Brake Control Module.
- If the DTC does not set
All OK.