Scan Tool Testing and Procedures

Cooling System Operation:

SYSTEM DESCRIPTION

COOLING FAN CONTROL
The ECM controls the cooling fan corresponding to the vehicle speed, engine coolant temperature, air conditioner system pressure and air conditioner ON signal. The control system has 3-step control [HIGH/LOW/OFF].
With the ignition key in the OFF position the cooling fans will operate for a maximum of 120 seconds if the engine coolant temperature reaches 96 °C (205 °F) or above.





CONSULT REFERENCE VALUE IN DATA MONITOR MODE
Specification data are reference values.

Terminals 13 Thru 14:

ECM TERMINALS AND REFERENCE VALUE
Remarks: Specification data are reference values, and are measured between each terminal and (25) (ECM ground) with a voltmeter.




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

CAUTION: When a malfunction is indicated, be sure to replace the coolant following the procedure in "Changing Engine Coolant", "ENGINE MAINTENANCE". Also, replace the engine oil.
a. 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", "RECOMMENDED FLUIDS AND LUBRICANTS".
b. After refilling coolant, run engine to ensure that no water-flow noise is emitted.

0VERALL FUNCTION CHECK

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.

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".







With Consult
3. Turn ignition switch "ON".
4. Perform "COOLING FAN" in "ACTIVE TEST" mode with CONSULT (LOW speed and HI speed).
5. If NG, go to "DIAGNOSTIC PROCEDURE".

OR







Without Consult
3. Start engine.
Be careful not to overheat engine.
4. Set temperature control lever to full cold position.
5. Turn air conditioner switch "ON".
6. Turn blower fan switch "ON".
7. Run engine at idle for a few minutes with air conditioner operating.
Be careful not to overheat engine.
8. Make sure that cooling fan operates at low speed.
9. Turn ignition switch "OFF".
10. Turn air conditioner switch and blower fan switch "OFF".
11. Disconnect engine coolant temperature sensor harness connector.
12. Connect 150 Ohm resistor to engine coolant temperature sensor harness connector.
13. Restart engine and make sure that cooling fan operates at higher speed than low speed.
Be careful not to overheat engine.
14. If NG, go to "DIAGNOSTIC PROCEDURE".







WIRING DIAGRAM

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DIAGNOSTIC PROCEDURE




MAIN 12 CAUSES OF 0VERHEATING

COMPONENT INSPECTION




COOLING FAN RELAYS -1, -2 AND -3




Check continuity between terminals (3) and (5), (6) and (7).
If NG, replace relay.

COOLING FAN MOTORS -1 AND -2
1. Disconnect cooling fan motor harness connectors.







2. Supply cooling fan motor terminals with battery voltage and check operation.

COOLING FAN MOTOR SHOULD OPERATE
If NG, replace cooling fan motor.