P0480
DTC P0480 (w/LF1)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.
DTC Descriptors
DTC P0480
- Cooling Fan Relay 1 Control Circuit
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The engine cooling fan system is composed of one cooling fan, a series of 5 relays, the engine control module (ECM), and the associated wiring. The cooling fan assembly includes two individual resistors mounted to each side of the cooling fan shroud. This combination of components enables the ECM to operate the cooling fan at 3 speeds using two fan control circuits.
To operate the fan, the ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.
Conditions for Running the DTC
* The ignition voltage is between 11-18 volts.
* The engine speed is greater than 400 RPM.
* The ECM driver transitions from ON to OFF or from OFF to ON.
* DTC P0480 runs continuously when the conditions above are met.
Conditions for Setting the DTC
P0480
The ECM detects an open circuit, short to ground, or a short to voltage on the cooling fan relay control circuit, for greater than 200 mS.
Action Taken When the DTC Sets
DTC P0480 is a Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P0480 is a Type B DTC.
Diagnostic Aids
* A condition with the powertrain relay or the bussed ignition voltage circuit to the cooling fan relay may set this DTC.
* The ECM has the capability of providing command to the fan relays even when a scan tool output control is being used. Always refer to the scan tool Cooling Fan Relay Command parameters to know which fans are being commanded ON by the ECM.
* The scan tool cooling fan output control operates as follows:
- Cooling Fan Relay 1 operates the fan at a low speed
- Cooling Fan Relay 2 and 3 operates the fan at a medium speed
- Cooling Fan Relay 1, 2 and 3 operates the fan at a high speed
* When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.
Reference Information
Schematic Reference
Engine Cooling Schematics (Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Cooling Fan Description and Operation (LAU) (Cooling Fan Description and Operation)Cooling Fan Description and Operation (LF1) (Cooling Fan Description and Operation)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning)for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool parameters listed below. Command the cooling fan ON and OFF with a scan tool. The parameters should display OK or Not Run in each of the commanded states.
* Cooling Fan Relay 1 Open Circuit Test Status
* Cooling Fan Relay 1 Low Voltage Test Status
* Cooling Fan Relay 1 High Voltage Test Status
2. Engine operating, observe the DTC information with a scan tool. DTC P0480 should not set.
3. 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.
Circuit/System Testing
1. Ignition OFF, disconnect and remove the underhood fuse block (UBEC) and housing.
2. Connect the engine harness connectors X2 and X3 to the UBEC.
3. Connect the red lead of a DMM to the control circuit terminal X1-33. Connect the black lead to ground. Set the DMM on the diode setting. Ignition ON, the DMM should display OL.
• If less than the specified range, test the relay coil control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
4. Command the cooling fan relay ON and OFF at low speed, with a scan tool. The DMM should transition from OL when commanded OFF to less than 1 V when commanded ON.
• If the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance or for a short to voltage. If the circuit tests normal, replace the K20 ECM.
5. If all circuits test normal, test or replace the X50A UBEC.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Fuse Block Replacement (Fuse Block Replacement)
* Control Module References (Programming and Relearning)for ECM replacement, setup, and programming