P0480

General Description

When the ambient air temperature is warm or the airflow across the engine is low, the engine coolant temperature can become hot. If the coolant temperature becomes too hot, it is possible that the engine could be damaged. The purpose of activating the engine compartment ventilation fan is to help reduce the engine coolant temperature to a level that is not threatening to engine performance and maintains the air-conditioning system pressure at safe levels.
Electric fan is responsible for causing air movement around the engine coolant radiator. The amount of air movement caused by the fan is controlled based on the Vehicle Speed, coolant temperature, A/C pressure status, A/C switch request status, and A/C clutch state. A duty cycle is determined based on these input parameters. This duty cycle corresponds to fan speed which correlates to the amount of air movement caused by the fan. The increased air movement enhances the heat exchanger function of the radiator in the confined space of the engine-compartment, thereby reducing the engine coolant temperature more quickly.

DTC Description

If the ECM detects short to ground, to battery or open circuit in the Cooling fan relay(low) , PCM sets P0480. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC Detecting Condition





Diagnostic Circuit Diagram





Monitor Scantool Data

1. Connect scantool to Data Link Connector(DLC).
2. IG "ON".
3. Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.
4. Read "DTC Status" parameter.




5. Is parameter displayed "Present fault"?�






Terminal and Connector inspection

1. Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?






Power Circuit Inspection

Check Voltage
1. IG "OFF" and disconnect Cooling fan relay(low).
2. IG "ON".
3. Measure voltage between battery power supply terminals of Cooling fan relay(low) harness connector and chassis ground.

Specification :Approx. B+


4. Is the measured voltage within specification ?






Control Circuit Inspection

Check signal wave form
1. IG "OFF" and disconnect Cooling fan relay(low).
2. IG "ON".
3. Measure voltage between Cooling fan relay control(Low) terminal of Cooling fan relay(low) harness connector and chassis ground.

Specification :Approx. B+


4. Is the measured voltage within specifications?






Verification of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.
1. Connect scantool and select "DTC" button.
2. Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
3. Read "DTC Status" parameter.
4. Is parameter displayed "History(Not Present) fault"?