Inspection Procedure 24: Fan Control Relay System.

OPERATION

The battery voltage is applied to the cooling fan control relay coil from the ignition switch <Vehicles without KOS> or IG2 relay <Vehicles with KOS>.
The engine-ECU connector terminal F/LO turns on the switch of the power transistor on the unit, and then turns on the switch of the relay by applying the electrical current to the cooling fan control relay coil.
When the cooling fan control relay is in ON position, the battery voltage is applied to the cooling fan motor from the cooling fan control relay.

FUNCTION

When the cooling fan control relay is in ON position, the fan motor rotates.

PROBABLE CAUSES

Failed cooling fan control relay
Failed cooling fan motor
Open/short circuit in or damage to the cooling fan control relay circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check cooling fan control relay.

Check cooling fan control relay (Refer to GROUP 14 - On-vehicle Service, Fan Control Relay Continuity Check ).

Q. Is the check result normal?

	Go to Step 2.

	Replace cooling fan control relay.

STEP 2. Check cooling fan motor itself.

Check cooling fan motor (Refer to GROUP 14 - On-vehicle Service, Cooling Fan Motor Check ).

Q. Is the check result normal?

	Go to Step 3.

	Replace cooling fan motor.

STEP 3. Perform voltage measurement at cooling fan control relay connector.

Disconnect connector and measure at harness side.
Voltage between terminal battery line and earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 4.

	Repair or replace the connector(s), or check and repair the harness of short circuit to earth, and open circuit in power supply line between battery and cooling fan control relay connector.

STEP 4. Perform voltage measurement at cooling fan control relay connector.

Disconnect connector and measure at harness side.
Ignition switch: "ON"
Voltage between terminal IG2 line and earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 5.

	NO <Vehicles without KOS> : Repair or replace the connector(s), or check and repair the harness of short circuit to earth, and open circuit in IG2 line between ignition switch and cooling fan control relay connector.

	NO <Vehicles with KOS> : Repair or replace the connector(s), or check and repair the harness of short circuit to earth, and open circuit in IG2 line between IG2 relay and cooling fan control relay connector.

STEP 5. Check of damage in power supply line between battery and cooling fan control relay connector.

Q. Is the check result normal?

	Go to Step 6.

	Repair the connector(s) or wiring harness.

STEP 6. Check of damage in IG2 line between ignition switch connector and cooling fan control relay connector.

Q. Is the check result normal?

	Go to Step 7.

	Repair the connector(s) or wiring harness.

STEP 7. Check of damage in IG2 line between IG2 relay connector and cooling fan control relay connector.

Q. Is the check result normal?

	Go to Step 8.

	Repair the connector(s) or wiring harness.

STEP 8. Perform voltage measurement at engine-ECU connector.

Disconnect connector and measure at harness side.
Ignition switch: "ON"
Voltage between terminal F/LO line and earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 9.

	Repair or replace the connector(s), or check and repair the harness of short circuit to earth, and open circuit in F/LO line between cooling fan control relay connector and engine-ECU connector.

STEP 9. Check of damage in F/LO line between cooling fan control relay connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 10.

	Repair the connector(s) or wiring harness.

STEP 10. Perform resistance measurement at cooling fan motor connector.

Disconnect connector and measure at harness side.
Resistance between terminal earth line and earth.

OK: Continuity (2 Ω or less)

Q. Is the check result normal?

	Go to Step 11.

	Check and repair harness between cooling fan motor connector and body earth. Repair or replace the connector, or check and repair the harness of damage in earth line between cooling fan motor connector and body earth.

STEP 11. Check of open circuit, short circuit, and damage in power supply line between cooling fan control relay connector and cooling fan motor connector.

Q. Is the check result normal?

	Go to Step 12.

	Repair the connector(s) or wiring harness.

STEP 12. M.U.T.-III actuator test.

Refer to actuator test reference table .

Item 13: Cooling fan motor

Q. Are the check results normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).

	Replace engine-ECU.