Trouble Diagnosis For Overheat (Cooling System)

SYSTEM DESCRIPTION

Cooling Fan Control:

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.

Operation:

Consult-II Reference Value In Data Monitor Mode:

ECM Terminals And Reference Value:

On Board Diagnosis Logic:

OVERALL 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-II (LOW speed and HI speed).
5. If NG, go to "DIAGNOSTIC PROCEDURE".

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".

EC-COOL/F-01:

EC-COOL/F-01 Connector View:

WIRING DIAGRAM

Super Multiple Junction (SMJ):

Part 1:

Part 2:

Part 3:

Part 4:

Part 5:

Part 6:

DIAGNOSTIC PROCEDURE

Main 12 Causes Of Overheating:

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.