Inspection Procedure 25: Fan control relay system <Vehicles with cooling fan>

OPERATION

The battery voltage is applied to the cooling fan control relay coil (terminal No. 3) from the ignition switch.
The engine-ECU <M/T> or engine-A/T-ECU <A/T> (terminal No. 17) 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 (terminal No. 1) from the cooling fan control relay (terminal No. 4).

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 cooling fan control relay circuit or loose connector contact
Failed engine-ECU <M/T> or engine-A/T-ECU <A/T>

DIAGNOSIS PROCEDURE

STEP 1. Connector check: A-10X cooling fan control relay connector

Q. Is the check result normal?

	Go to Step 2 .

	Repair or replace the connector.

STEP 2. Check cooling fan control relay.

Check cooling fan control relay (Refer to GROUP 55 - On-vehicle Service - Relay Continuity Check ).

Q. Is the check result normal?

	Go to Step 3 .

	Replace the fan control relay.

STEP 3. Connector check: A-29 cooling fan motor connector

Q. Is the check result normal?

	Go to Step 4 .

	Repair or replace the connector.

STEP 4. Check cooling fan motor.

Check cooling fan motor (Refer to GROUP 55 - Condenser Assembly - Condenser Assembly Inspection ).

Q. Is the check result normal?

	Go to Step 5 .

	Replace cooling fan motor.

STEP 5. Perform voltage measurement at A-10X cooling fan control relay connector.

Disconnect connector and measure at harness side.
Voltage between terminal No. 3 and earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 6 .

	Check intermediate connectors A-15, D-241, D-401 and D-403, and repair if necessary. If intermediate connectors are normal, check and repair harness between A-10X (terminal No. 3) cooling fan control relay connector and battery. Check power supply line for open/short circuit.

STEP 6. Perform voltage measurement at A-10X cooling fan control relay connector.

Disconnect connector and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 5 and earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 8 .

	Go to Step 7 .

STEP 7. Connector check: D-309 ignition switch connector

Q. Is the check result normal?

	Check intermediate connectors A-15, D-241, D-401 and D-403, and repair if necessary. If intermediate connectors are normal, check and repair harness between A-10X (terminal No. 3) cooling fan control relay connector and D-309 (terminal No. 2) ignition switch connector. Check power supply line for open/short circuit.

	Repair or replace the connector.

STEP 8. Check harness between battery and A-10X (terminal No. 5) cooling fan control relay connector.

note

Before checking harness, check intermediate connector A-16, and repair if necessary.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 9 .

	Repair the damaged harness wire.

STEP 9. Check harness between D-309 (terminal No. 2) ignition switch connector and A-10X (terminal No. 3) cooling fan control relay.

note

Before checking harness, check intermediate connectors A-15, D-241, D401 and D-403 and repair if necessary.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 10 .

	Repair the damaged harness wire.

STEP 10. Connector check: D-243 engine-ECU <M/T> connector or D-212 engine-A/T-ECU <A/T> connector

Q. Is the check result normal?

	Go to Step 11 .

	Repair or replace the connector.

STEP 11. Perform voltage measurement at D-243 engine-ECU <M/T> connector or D-212 engine-A/T-ECU <A/T> connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 17 and earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 12 .

	Check intermediate connector A-03 <L.H. drive vehicles> or D-137 <R.H. drive vehicles>, and repair if necessary. If intermediate connector is normal, check and repair harness between A-10X (terminal No. 1) cooling fan control relay connector and D-243 (terminal No. 17) engine-ECU <M/T> connector or D-212 (terminal No. 17) engine-A/T-ECU <A/T> connector. Check signal line for open/short circuit.

STEP 12. Check harness between A-10X (terminal No. 1) cooling fan control relay connector and D-243 (terminal No. 17) engine-ECU <M/T> connector or D-212 (terminal No. 17) engine-A/T-ECU <A/T> connector.

note

Before checking harness, check intermediate connector A-03 <L.H. drive vehicles> or D-137 <R.H. drive vehicles>, and repair if necessary.

Check signal line for damage.

Q. Is the check result normal?

	Go to Step 13 .

	Repair the damaged harness wire.

STEP 13. Perform resistance measurement at A-29 cooling fan motor connector.

Disconnect connector and measure at harness side.
Resistance between terminal No. 2 and earth.

OK: Continuity (2 Ω or less)

Q. Is the check result normal?

	Go to Step 15 .

	Go to Step 14 .

STEP 14. Connector check: A-29 cooling fan motor connector.

Q. Is the check result normal?

	Check and repair harness between A-29 (terminal No. 2) cooling fan motor connector and earth. Check earthing line for damage.

	Repair or replace the connector.

STEP 15. Check harness between A-29 (terminal No. 1) cooling fan motor connector and A-10X (terminal No. 4) cooling fan control relay connector.

note

Before checking harness, check intermediate connector A-14, and repair if necessary.

Check power supply line for open/short circuit and damage.

Q. Is the check result normal?

	Go to Step 16 .

	Repair the damaged harness wire.

STEP 16. M.U.T.-III actuator test

Refer to Actuator Test Reference Table .

Item 13: Cooling fan motor

Q. Is the check result normal?

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

	Replace the engine-ECU <M/T> or engine-A/T-ECU <A/T>.