P0480
DTC P0480 or P0481 (LE5) (2.4L Without Hybrid)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0480
- Low Speed Cooling Fan Relay Control Circuit
DTC P0481
- High Speed Cooling Fan Relay Control Circuit
Diagnostic Fault Information
Circuit/System Description
The engine control module (ECM) commands the fans ON in high speed or low speed. In low speed, the fans are configured in series. In high speed, the fans are configured in parallel.
In low speed operation, the ECM applies ground to the coil side of the low speed fan relay, which is FAN AUX relay. Voltage is applied directly to the left cooling fan through the switch side of low speed fan relay. The right fan is connected in series to the left fan through the de-energized series/parallel relay, which is FAN CTRL relay so that both fans operate at low speed.
In high speed operation, the ECM applies a ground to the coil side of low speed fan relay, series/parallel relay, and high speed fan relay, which is FAN MAIN. Voltage is applied directly to the right cooling fan through the switch side of high speed relay. The left cooling fan obtains voltage through low speed relay and ground through series/parallel relay.
When the ECM is commanding a fan relay ON, the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding a fan relay OFF, the voltage of the control circuit should be high, near battery voltage.
Conditions for Running the DTC
* The engine is running.
* The system voltage is between 11-18 volts.
Conditions for Setting the DTC
* An improper voltage level has been detected on the cooling fan relay control circuit.
* The condition must be present for a minimum of 30 seconds.
Action Taken When the DTC Sets
DTCs P0480 and P0481 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P0480 and P0481 are Type B DTCs.
Reference Information
Schematic Reference
Engine Cooling Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Cooling Fan Description and Operation (Except LAT) (Description and Operation)Cooling Fan Description and Operation (LAT) (Description and Operation)Cooling Fan Description and Operation (LCS) (Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Verify cooling fan operation using the scan tool commands listed below:
* Fan Relay 1 ON-Both fans run at low speed.
* Fan Relays 2 and 3 ON-The right fan runs at high speed, the left fan is OFF.
* Fan Relays 1, 2 and 3 ON-Both fans run at high speed.
Circuit/System Testing
1. Ignition OFF, disconnect the 3 cooling fan relays listed below.
* FAN AUX relay
* FAN CNTRL relay
* FAN main relay
2. Ignition ON, verify that a test lamp illuminates between ground and the appropriate battery voltage circuit terminal 85.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
3. Verify that a test lamp does not illuminate between terminal 85 and terminal 86 of each relay.
• If the test lamp illuminates, test the control circuit for a short to ground. If the circuit test normal, replace the ECM.
4. Remove the test lamp.
5. Ignition ON, command the affected relay ON using a scan tool. Verify the affected scan tool FC Relay Control Ckt. Short Volts Test Status Parameter is OK.
* For the FAN AUX relay, use the scan tool Fan Relay 1 command.
* For the FAN CNTRL and FAN MAIN relays, use the scan tool Relay 2 and 3 command.
• If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
6. Install a 3A fused jumper wire between terminal 86 and terminal 85. Command the affected relay ON with a scan tool. Verify the scan tool Relay Control Ckt Short Volts 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.
7. If all circuits and the ECM test normal, replace the affected relay.
Repair Instructions
* Underhood Electrical Center or Junction Block Replacement (HP7) (Service and Repair)Underhood Electrical Center or Junction Block Replacement (HP5) (Service and Repair)
* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Cooling Fan and Shroud Replacement (LAT) (Service and Repair)Cooling Fan and Shroud Replacement (HP5) (Service and Repair)Cooling Fan and Shroud Replacement (LE5, LZ4, LY7) (Service and Repair)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming.
Repair Verification
Ignition ON, command the relay ON and OFF with a scan tool. Feel or listen to verify that the relay turns ON and OFF with each command.