P0480

P0480

Component Location:

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 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
The Delphi EMS system provides for a method of electrically controlling when the fan(s) should be activated and deactivated based on a variety of engine conditions, including the coolant temperature, vehicle speed, air conditioning switch status and air conditioning pressure status. As the coolant temperature air conditioning pressure rises, increased airflow is required to reduce the engine temperature and A/C system pressure. The engine cooling fan(s) are activated to increase airflow across the engine components.
Checking power supply to cooling fan relay to cooling fan module and control signals under detecting condition, if the PCM detects short to ground, to battery or open circuit, PCM sets P0480. MIL (Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC Detecting Condition:

Schematic Diagram:

Monitor DTC Status
1. Check DTC Status
1. Connect scantool to Data Link Connector (DLC).
2. IG "ON".
3. Select "Diagnostic Trouble Codes (DTCs)" mode, and then Press F5 (INFO) to check DTC's information from the DTCs menu
4. Read "DTC Status" parameter.

5. Is parameter displayed "Present fault"?

YES - Go to "Terminal and Connector inspection" procedure.

NO - Fault is intermittent caused by poor contact in the sensors and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

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?

YES - Repair as necessary and go to "Verification of Vehicle Repair" procedure

NO - Go to " Power Circuit Inspection " procedure

Power Supply Circuit Inspection
1. IG "OFF" and disconnect Cooling fan module connector.
2. IG "ON" & ENG "OFF"
3. Measure voltage between terminal 1 of Cooling fan module harness connector and chassis ground.

Specification : Approx. B+

4. Is the measured voltage within specification?

YES - Go to "Control Circuit Inspection" procedure.

NO
- Check if cooling fan fusible link 60A is open or not installed.
- Check if cooling fan relay is not installed or faulty
- Check if the line between cooling fan relay and Cooling fan module is open.
- Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.

Control Circuit Inspection
1. IG "OFF"
2. Disconnect Cooling fan module connector.
3. IG "ON" & ENG "OFF"
4. Measure signal waveform at terminal 2 of cooling fan module.

Reference signal waveform :

5. Is the measured signal waveform normal?

YES - If the problem is corrected after substituting with a known - good Cooling Fan module, replace it. If the problem is pending, check for proper operating after substituting with a known - good PCM. and then if the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.

NO
- Check that harness connected at engine compartment junction block is disconnected or not.
- Check the line between terminal 2 of Cooling Fan module harness connector and terminal 66 of PCM harness connector for open.
- Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

NOTE: There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. After testing PCM on the vehicle, use this function to reuse the PCM on the others

Verification of Vehicle Repair
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode
2. Press F5 (INFO) and confirm that "DTC Readiness Flag" indicates "Complete". 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"?

YES - System performing to specification at this time. Clear the DTC

NO - Go to the applicable troubleshooting procedure.