STEP 1. Using scan tool (M.U.T.-IIISE), diagnose the CAN bus line
STEP 2. Check of short to ground or open circuit in STP1 line between stoplight switch connector and KOS&OSS-ECU connector
STEP 3. Check of short to ground or open circuit in BKLP line between stoplight switch connector and ETACS-ECU connector
STEP 4. Using scan tool (M.U.T.-IIISE), check the other system data list
STEP 5. Using scan tool (M.U.T.-IIISE), check the data list
STEP 6. Check whether the DTC is set again.