Cooling Fan Always On

Cooling Fan Always On (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.

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 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 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 relay, series/parallel relay, and high speed relay, which is FAN MAIN relay. Voltage is applied directly to the right cooling fan through the switch side of high speed relay. The left cooling fan obtains voltage through fan low speed 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.

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

1. If DTC P0480 or P0481 are set, perform those diagnostics first.
2. Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
3. 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 low speed fan relay, which is FAN AUX relay.
2. Ignition ON, observe that both fans are now OFF.

• If both fans are OFF, replace low speed relay. If either fan is still activated, remove high speed fan relay, which is FAN MAIN relay. If both fans are now OFF, replace high speed relay. If either fan is still activated, test for a short to voltage in the fan voltage supply circuit.

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)

Repair Verification

Ignition ON, command the relay ON and OFF with a scan tool. Observe to verify that the fan turns ON and OFF with each command.