Cooling Fan Control System Inspection

Cooling Fan Operation:

Cooling fan
1. Verify the engine is cold.
2. Turn the ignition switch ON.
3. Verify the cooling fan is not operating.
4. If the cooling fan is operating:




1. Connect the SSTs (NGS tester) to the DLC.
2. Select the "ACTIVE COMMAND" then "OUTPUT TEST MODE" function on the NGS tester display.
3. Select the "ALL OFF" and verify the cooling fan signal is OFF.

4. If the cooling fan control signal is ON check:
- Cooling fan relay stuck in closed position.
- Short to ground circuit between cooling fan relay and PCM.
- Short to power in circuit between cooling fan relay.
- DTCs for ECT sensor.
- P0117, P0118, P0125, P1116, P1117.

5. If the cooling fan is OFF, check the following.
- Short to ground circuit between A/C switch and PCM.
- DTC for ECT sensor.
- P0117, P0118, P0125, P1116, P1117.

5. Start the engine.
6. Verify that the cooling fan is operating when engine is hot.
7. If the cooling fan does not operate, do as follows.




1. Connect the SSTs (NGS tester) to the DLC.
2. Select "Active Command" mode.
3. Select "Output Test Mode".
4. Select "ALL ON" mode.
5. Press "Start".
6. If the cooling fan operates, check the ECT sensor DTCs.
- P0117, P0118, P0125, P1116, P1117.

7. If the cooling fan does not operate, do as follows.
1. Select "ALL ON". Operate cooling fan by selecting "Start", and verify that operational sound is heard from the cooling fan relay.
2. If the operational sound is heard, check the wiring harnesses and connectors and cooling fan motor.
3. If operational sound is heard, check cooling fan relay and open circuit in wiring harnesses and connectors.

8. Turn the A/C switch and fan switch ON.
9. Verify the cooling fan is operating.
10. If fan does not operate, check A/C system.