Cooling Fan Control System Inspection

Cooling Fan Control System Inspection

Cooling Fan System Operation (at Idle):

1. Connect the M-MDS to the DLC-2.
2. Verify that DTC PO480 or PO481 is not displayed.
- If DTC PO480 and/or PO481 are displayed, perform DTC inspection.

3. Access the ECT PID.
4. Verify that the ECT PID is 97 °C (208 °F) or less.
5. Verify that the A/C switch and fan switch are off.
6. Start the engine and let it idle.
7. Verify that the cooling fans are not operating.
- If the cooling fans are operating at low speed, inspect for the following:
- Cooling fan relay No.1 (stuck closed)
- Wiring harnesses and connectors (cooling fan relay No.1-PCM terminal 5X) (short to GND)

- If the cooling fan No.1 is not operating, but cooling fan No.2 is operating, inspect for the following:
- Cooling fan relay No.3 (stuck closed)
- Wiring harnesses and connectors (cooling fan relay No.3-PCM terminal 5AD) (short to GND)

8. Warm up engine 97 °C (208 °F) or more and verify that the cooling fans are operating at low speed.
- If cooling fans are not operating, inspect for the following:
- Cooling fan relay No.1 (stuck open)
- Wiring harnesses and connectors (battery - cooling fan relay No.1-cooling fan relay No.2) (open)
- Wiring harnesses and connectors (main relay - cooling fan relay No.1 PCM terminal 5X) (open)

- If cooling fan relay No.1 is operating at high speed, inspect for the following:
- Cooling fan relay No.2 (stuck close)

9. Stop the engine.
10. Disconnect the ECT sensor.

Note: When the ECT sensor connector is disconnected, the PCM stores DTC PO118.

11. Start the engine and let it idle.
12. Verify that the cooling fans are operating at high speed.
- If the cooling fans are operating at low speed, inspect for the following:
- Cooling fan relay No.2 (stuck open)
- Cooling fan relay No.3 (stuck open)
- Wiring harnesses and connectors (open circuit at battery-cooling fan relay No.3-cooling fan N0.2- GND)
- Wiring harnesses and connectors (open circuit at main relay-cooling fan relay No.2 -PCM terminal 5AD)
- Wiring harnesses and connectors (open circuit at main relay-cooling fan relay No.3 -PCM terminal 5AD)

- If cooling fan No.1 is operating at high speed, but cooling fan No.2 is not operating, inspect for the following:
- Cooling fan relay No.3 (stuck open)
- Wiring harnesses and connectors (open circuit at main relay-cooling fan relay No.3 -PCM terminal 5AD)

- If cooling fan No.2 is operating at high speed, but cooling fan No.1 is not operating, inspect for the following:
- Cooling fan relay No.2 (stuck open)
- Wiring harnesses and connectors (open circuit at main relay-cooling fan relay No.2 -PCM terminal 5AD)

13. Clear the DTC from the PCM memory.