Trouble Diagnosis For Overheat (Cooling System)

SYSTEM DESCRIPTION

Cooling Fan Control:

Operation:

Consult-II Reference Value In Data Monitor Mode:

ECM Terminals And Reference Value:

ON BOARD DIAGNOSIS LOGIC
If the cooling fan or another component in the cooling system malfunctions, engine coolant temperature will rise. When the engine coolant temperature reaches an abnormally high temperature condition, a malfunction is indicated.

Malfunction is detected when engine coolant temperature reaches an abnormally high temperature.

CAUTION: When a malfunction is indicated be sure to replace the coolant, follow the procedure in "Changing Engine Coolant". Also, replace the engine oil.
1. Fill radiator with coolant up to specified level with a filling speed of 2 liters per minute like pouring coolant by kettle. Be sure to use coolant with the proper mixture ratio. Refer to "Anti-freeze Coolant Mixture Ratio".
2. After refilling coolant, run engine to ensure that no water-flow noise is emitted.

POSSIBLE CAUSE
- Harness or connectors
(The cooling fan circuit is open or shorted.)
- Cooling fan
- Radiator hose
- Radiator
- Radiator cap
- Water pump
- Thermostat

For more information, refer to "MAIN 12 CAUSES OF OVERHEATING".

Overall Function Check
Use this procedure to check the overall function of the cooling fan. During this check, a DTC might not be confirmed.

WARNING: Never remove the radiator cap when the engine is hot. Serious burns could be caused by high pressure fluid escaping from the radiator.
Wrap a thick cloth around cap. carefully remove the cap by turning it a quarter turn to allow built-up pressure to escape. Then turn the cap all the way off.

With CONSULT-II

1. Check the coolant level in the reservoir tank and radiator.
Allow engine to cool before checking coolant level.
If the coolant level in the reservoir tank and/or radiator is below the proper range, skip the following steps and go to "Diagnostic Procedure".
2. Confirm whether customer filled the coolant or not. If customer filled the coolant, skip the following steps and go to "Diagnostic Procedure".
3. Turn ignition switch ON.

4. Perform "COOLING FAN" in "ACTIVE TEST" mode with CONSULT-II.
5. Make sure that cooling fan operates.
6. If NG, go to "Diagnostic Procedure".

Without CONSULT-II
1. Check the coolant level in the reservoir tank and radiator.
Allow engine to cool before checking coolant level.
If the coolant level in the reservoir tank and/or radiator is below the proper range, skip the following steps and go to "Diagnostic Procedure".
2. Confirm whether customer filled the coolant or not. If customer filled the coolant, skip the following steps and go to "Diagnostic Procedure".
3. Turn ignition switch OFF.

4. Disconnect engine coolant temperature sensor harness connector.
5. Connect 150 Ohms resistor to engine coolant temperature sensor harness connector.
6. Start engine and make sure that cooling fan operates.
Be careful not to overheat engine.
7. If NG, go to "Diagnostic Procedure".