Cooling Fan Always On

Cooling Fan Always On (2.4L)

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.

Circuit/System Description

The engine cooling fan system is composed of one cooling fan, 2 relays, the engine control module (ECM), and the associated wiring. The cooling fan assembly includes 1 resistor mounted in the cooling fan shroud. This combination of components enables the ECM to operate the cooling fan at 2 speeds using two fan control circuits. The ECM will operate the cooling fan at either Low or High speed based on the cooling requirements.

Diagnostic Aids

* 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 the fan at a high speed

* KR20 cooling fan relay identification:

- KR20C COOL FAN LOW Relay
- KR20D COOL FAN HI Relay

* 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 Views)
Description and Operation

Cooling Fan Description and Operation (3.0L) (Description and Operation)Cooling Fan Description and Operation (2.4L) (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)

Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information

Circuit/System Verification

1. ignition ON, observe the DTC information with a scan tool. Verify that DTC P0480 or P0481 is not set.

• If a DTC is set, refer to DTC P0480 or P0481 (w/LF1) (P0480)DTC P0480 or P0481 (w/LAF) (P0480).

2. Ignition ON, observe the scan tool Cooling Fan Relay 1 and Cooling Fan Relays 2 Command parameters. The parameters should display OFF.
3. Ignition ON, observe that the fan is not activated.

Circuit/System Testing

Note: The following tests must be performed on each cooling fan relay.

1. Ignition OFF, disconnect the KR20 cooling fan relays one at a time.
2. Ignition ON, observe that the cooling fans are not activated.

• If the fan is activated, test for a short to voltage in the relay controlled output circuits of the engine cooling fan.
• If the fans are not activated, test or replace the appropriate KR20 cooling fan relay.

Component Testing

1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 70-110 ohm between terminals 85 and 86.

• If not within the specified range, replace the KR20 cooling fan relay.

3. Measure the resistance between the terminals listed below. The DMM should display OL.

* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87

• If not the specified range, replace the KR20 cooling fan relay.

4. Install a 20 A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohm between terminals 30 and 87.

• If greater than the specified range, replace the KR20 cooling fan relay.

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))