DTC P0480, P0481, or P0482 Hybrid

The hybrid engine cooling fan system consists of two electrical cooling fans, two resistors, three engine control module (ECM) fan output control drivers, and five fan relays. The relays are arranged in a series/parallel configuration that allows the ECM to operate the fans at low, medium, or high speed depending on engine cooling requirements. The ECM controls the five relays by grounding the relay control circuits.

During low speed operation, the ECM supplies the ground path for the FAN LO relay control circuit. This energizes the FAN LO relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the de-energized FAN CNTRL relay, through the right cooling fan in-line resistor, and through the right cooling fan. The result is a series circuit with both fans running at low speed.

During medium speed operation the ECM grounds one control circuit that energizes a bank of three relays consisting of the FAN Mid 1 relay, the FAN CNTRL relay, and the FAN Mid 2 relay. When these three relays are energized the Mid 1 relay supplies battery voltage to the left cooling fan through the left cooling fan resistor. A ground path is provided for the left fan through the energized FAN CNTRL relay. At the same time the Mid 2 relay is energized which applies battery voltage to the right cooling fan through the right cooling fan resistor. The result is a parallel circuit where each fan has voltage applied through a resistor which causes each fan to operate at reduced speed.

During high speed operation the ECM grounds all three relay control circuits which activates all five relays. This allows full battery voltage to be applied to the right cooling fan from the FAN HI relay, and full battery voltage to be applied to the left fan from the FAN LO relay. The left fan is grounded through the FAN CNTRL relay. In this arrangement each fan has full battery voltage applied and each fan has its own ground path. The result is a parallel circuit with both fans running at high speed.

Refer to Engine Cooling Schematics .

An improper voltage level has been detected on the cooling fan relay control circuit.

DTCs P0480, P0481, and P0482 are Type B DTCs.

DTCs P0480, P0481, and P0482 are Type B DTCs.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

P0480

1. Ignition ON, command the FC Relay 1 Command ON and OFF with a scan tool while observing the following control circuit status parameters.

•	FC Relay 1 CKT Short GND Test Status

•	FC Relay 1 CKT Open Test Status

•	FC Relay 1 CKT Short Volts Test Status

•	Each parameter should toggle between OK and Not Run or Not Run and OK.

2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

P0481

1. Ignition ON, command the FC Relay 2 Command ON and OFF with a scan tool while observing the following control circuit status parameters.

•	FC Relay 2 CKT Short GND Test Status

•	FC Relay 2 CKT Open Test Status

•	FC Relay 2 CKT Short Volts Test Status

•	Each parameter should toggle between OK and Not Run or Not Run and OK.

2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

P0482

1. Ignition ON, command the FC Relay 3 Command ON and OFF with a scan tool while observing the following control circuit status parameters.

•	FC Relay 3 CKT Short GND Test Status

•	FC Relay 3 CKT Open Test Status

•	FC Relay 3 CKT Short Volts Test Status

•	Each parameter should toggle between OK and Not Run or Not Run and OK.

2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description .
2. Ignition ON, verify the scan tool hood position parameter displays Open.

⇒	If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.

3. Ignition OFF, disconnect the FAN CNTRL relay.
4. Connect a 30A fused jumper between the normally-open switch contacts terminal 30 and terminal 87 at the FAN CNTRL relay connector in order to complete the left fan ground circuit. Leave this jumper in place for the remainder of this procedure.
5. Ignition OFF, disconnect the affected relays.

•	For DTC P0480 -- FAN LO relay

•	For DTC P0481 -- FAN HI relay

•	For DTC P0482

-	FAN Mid 1 relay

-	FAN CNTRL relay

-	FAN Mid 2 relay

6. Verify that a test lamp does not illuminate between B+ and the affected relay control circuit terminal.

•	FAN LO relay -- Terminal 86

•	FAN Mid 1 relay -- Terminal 86

•	FAN CNTRL relay -- Terminal 85

•	FAN Mid 2 relay -- Terminal 86

•	FAN HI relay -- Terminal 86

⇒	If the test lamp illuminates, test the relay control circuit for a short to ground. If the circuit tests normal, replace the ECM.

7. Install a 3A fused jumper wire between the affected relay control circuit terminal and ground.

•	FAN LO relay -- Terminal 86

•	FAN Mid 1 relay -- Terminal 86

•	FAN CNTRL relay -- Terminal 85

•	FAN Mid 2 relay -- Terminal 86

•	FAN HI relay -- Terminal 86

8. Command the affected relay ON with a scan tool. Verify the scan tool affected relay control circuit Short Grnd Test Status Parameter is Fault.

⇒	If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

9. Connect a 30A fused jumper between the positive voltage terminal at the battery and the fan voltage supply circuit terminal at the affected relay connector and verify fan activation.

•	FAN LO relay -- Terminal 30

•	FAN Mid 1 relay -- Terminal 30

•	FAN CNTRL relay -- Terminal 87A

•	FAN Mid 2 relay -- Terminal 87

•	FAN HI relay -- Terminal 87

⇒

If the fan does not activate, test the engine coolant fan resistor for an open, if the resistor tests normal, test the fan voltage supply circuit for a short to ground or open/high resistance. If the circuit tests normal, test the fan ground circuit for an open/high resistance. If the circuits test normal, replace the fan.

10. Ignition ON, connect a 30A fused jumper between the relay switch voltage supply circuit terminal and the fan voltage supply circuit terminal at the affected relay connector and verify fan activation.

•	FAN LO relay -- Terminal 87 to Terminal 30

•	FAN Mid 1 relay -- Terminal 87 to Terminal 30

•	FAN Mid 2 relay -- Terminal 30 to Terminal 87

•	FAN HI relay -- Terminal 30 to Terminal 87

⇒	If the fan does not activate, test the affected relay switch voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.

11. Ignition ON, verify that a test lamp illuminates between the affected relay coil voltage supply circuit terminal and ground.

•	FAN LO relay -- Terminal 85

•	FAN Mid 1 relay -- Terminal 85

•	FAN CNTRL relay -- Terminal 86

•	FAN Mid 2 relay -- Terminal 85

•	FAN HI relay -- Terminal 85

⇒	If the test lamp does not illuminate, test the affected relay coil voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.

12. If all circuits and the ECM test normal, replace the affected relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.