Inspection Procedure 24: Fan Control Relay System

OPERATION

The battery voltage is applied to the fan control relay (terminal No. 3) from the engine control relay (terminal No. 1) and is earthed to the vehicle body from the fan control relay (terminal No. 1).
The battery voltage is applied to the fan control relay (terminal No. 4).
When the fan control relay is in ON position, the battery voltage is supplied to the fan controller (terminal No. 3) from the fan control relay (terminal No. 2).

FUNCTION

When the engine control relay is in ON position, the fan control relay is also simultaneously placed in ON position. Accordingly, the battery voltage is supplied to the fan controller.

PROBABLE CAUSE

Failed fan control relay
Failed fan controller
Failed radiator fan motor
Failed condenser fan motor
Open/short circuit in fan control relay circuit or loose connector contact
Failed engine-A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: A-13X fan control relay connector

Q. Is the check result normal?

Go to Step 2 .

Repair or replace.

STEP 2. Check fan control relay.

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

Q. Is the check result normal?

	Go to Step 3 .

	Replace fan control relay.

STEP 3. Perform resistance measurement at A-13X fan control relay connector.

Remove relay and measure at relay box side.
Resistance between terminal No. 1 and earth.

OK: 2 Ω or less

Q. Is the check result normal?

Go to Step 4 .

Check earth connector A-25, and repair if necessary. If earth connector is normal, check and repair harness between A-13X (terminal No. 1) fan control relay connector and A-25 (terminal No. 5) earth connector.

Check earthing line for open circuit and damage.

STEP 4. Perform voltage measurement at A-13X fan control relay connector.

Remove relay and measure at relay box side.
Ignition switch: ON
Voltage between terminal No. 3 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 6 .

Go to Step 5 .

STEP 5. Connector check: B-15X engine control relay connector

Q. Is the check result normal?

Check power supply line for open/short circuit.

Repair or replace.

STEP 6. Perform voltage measurement at A-13X fan control relay connector.

Remove relay, and measure at relay box side.
Voltage between terminal No. 4 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 7 .

Check power supply line for open/short circuit.

STEP 7. Connector check: A-26 fan controller connector

Q. Is the check result normal?

Go to Step 8 .

Repair or replace.

STEP 8. Perform voltage measurement at A-26 fan controller connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 3 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 12 .

Go to Step 9 .

STEP 9. Check harness between A-13X (terminal No. 2) fan control relay connector and A-26 (terminal No. 3) fan controller connector.

Check power supply line for open/short circuit.

Q. Is the check result normal?

Go to Step 10 .

Repair.

STEP 10. Connector check: B-15X engine control relay connector

Q. Is the check result normal?

Go to Step 11 .

Repair or replace.

STEP 11. Check harness between B-15X (terminal No. 1) engine control relay connector and A-13X (terminal No. 3) fan control relay connector.

note

Before checking harness, check intermediate connectors A-16 and C-116, and repair if necessary.

Check power supply line for damage.

Q. Is the check result normal?

Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points

Repair.

STEP 12. Connector check: C-110 engine-A/T-ECU connector

Q. Is the check result normal?

Go to Step 13 .

Repair or replace.

STEP 13. Fan motor drive test.

Disconnect C-110 engine-A/T-ECU connector.
Ignition switch: ON

OK: Fan motor rotates.

Q. Is the check result normal?

Go to Step 14 .

Go to Step 15 .

STEP 14. M.U.T.-III actuator test

Item 21: Fan controller

OK: Fan motor rotates.

Q. Is the check result normal?

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

	Replace engine-A/T-ECU.

STEP 15. Perform voltage measurement at C-110 engine-A/T-ECU connector.

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

OK: 4.9 - 5.1 V

Q. Is the check result normal?

Go to Step 16 .

Go to Step 18 .

STEP 16. Check harness between A-13X (terminal No. 4) fan control relay connector and battery.

Check power supply line for damage.

Q. Is the check result normal?

Go to Step 17 .

Repair.

STEP 17. Check harness between A-13X (terminal No. 2) fan control relay connector and A-26 (terminal No. 3) fan controller connector.

Check power supply line for damage.

Q. Is the check result normal?

Replace fan motor and fan controller.

Repair.

STEP 18. Check harness between A-26 (terminal No. 2) fan controller connector and C-110 (terminal No. 17) engine-A/T-ECU connector.

note

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

Check earthing line for short circuit.

Q. Is the check result normal?

Replace fan motor and fan controller.

Repair.