Inspection Procedure 18: Overheating


COMMENTS ON TROUBLE SYMPTOM



  • The failure could possibly be caused by the failed engine cooling system, defective cooling fan system, faulty engine coolant temperature sensor and so on.

PROBABLE CAUSES



  • Insufficient amount or deteriorated quality of engine coolant
  • Failed cooling fan system
  • Failed engine coolant temperature sensor
  • Failed thermostat
  • Failed water pump
  • Failed radiator core
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code

Q. Is the diagnosis code set?
Inspection chart for diagnosis code (Refer to ).
Go to Step 2 .

STEP 2. Check engine coolant.
note When the engine coolant level is too low, check for any section that cases leakage and repair, if necessary.

  • Check engine coolant (Refer to GROUP 14 - On-vehicle Service - Engine Coolant Leak Check ).

Q. Is the check result normal?
Go to Step 3 .
Replace or fill the engine coolant.

STEP 3. M.U.T.-III actuator test

  • Item 14: Cooling fan motor
OK: Fan motor rotates at high speed.

Q. Is the check result normal?
Go to Step 4 .
Check fan control relay system (Refer to GROUP 14 - Troubleshooting ).

STEP 4. M.U.T.-III data list

  • Item 6: Engine coolant temperature sensor
OK:
    Engine cold state: At ambient temperature (atmospheric temperature) or equivalent.
    Engine hot state: At 80 - 120°C

Q. Is the check result normal?
Go to Step 5 .
Check engine coolant temperature sensor system. Check code No. P0117: engine coolant temperature sensor circuit low input (Refer to ). Check code No. P0118: engine coolant temperature sensor circuit high input (Refer to ).

STEP 5. Check thermostat.

  • Check thermostat (Refer to GROUP 14 - Thermostat - Inspection ).

Q. Is the check result normal?
Go to Step 6 .
Replace the thermostat.

STEP 6. Check water pump.

  • Check water pump (Refer to GROUP 14 - On-vehicle Service - Water Pump Coolant Leak Check ).

Q. Is the check result normal?
Replace the radiator.
Replace the water pump.