Cooling Fan Inoperative

Cooling Fan Inoperative (LEA)

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 activates the applicable relay by grounding the control circuit with a solid state device called a driver. Each driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. 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

* 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 [1][2]Cooling System

Connector End View Reference

* Component Connector End Views Sunshade - Left Front

* Electrical Center Identification Views

Description and Operation

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

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 Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0480, P0481, P0691, P0692, P0693, or P0694 should not set.

• If a DTC is set, refer to DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LFW) P0480DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LEA) P0480.

2. Command the cooling fan ON and OFF at Low and High speed with a scan tool. The cooling fan should turn ON and OFF in each of the commanded states.

Circuit/System Testing

1. Ignition OFF, disconnect the G10 cooling fan harness connector.

2. Disconnect the R10 cooling fan resistor harness connector.

3. Test for less than 1.0 ohms between the G10 cooling fan ground circuit terminal 2 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

4. Ignition ON, connect a test lamp between ground and the G10 cooling fan circuit terminal 1. Command the cooling fan ON at high speed with a scan tool. The test lamp should illuminate as commanded.

• If the test lamp does not illuminate, test the high speed relay controlled output circuit and B+ supply circuit for a short to ground or for an open/high resistance. If the circuits test normal and the B+ fuse is open, test or replace the G10 cooling fan motor.

• If the circuits and B+ fuse test normal, test or replace the KR20D fan relay.

5. Connect a test lamp between the R10 fan resistor circuit terminal 1 and ground. Command the cooling fan ON at low speed with a scan tool. The test lamp should illuminate.

• If the test lamp does not illuminate, test the low speed relay controlled output circuit and B+ supply circuit for a short to ground or for an open/high resistance. If the circuits test normal and the B+ fuse is OK, test or replace the KR20C fan relay.

• If necessary, replace the B+ fuse.

6. Ignition OFF, connect the R10 fan resistor harness connector.

7. Ignition ON, connect a test lamp between ground and the G10 cooling fan circuit terminal 1. Command the cooling fan ON at low speed with a scan tool. The test lamp should illuminate as commanded.

• If the test lamp does not illuminate, test the low speed relay controlled output circuit for a short to ground or an open/high resistance between R10 resistor terminal 2 and the J110 splice. If the circuit tests normal, test or replace the R10 cooling fan resistor.

8. If all of the circuits and components test normal, test or replace the G10 cooling fan motor.

Component Testing

KR20 Cooling Fan Relay

1. Ignition OFF, disconnect the cooling fan relay.

2. Test for 70-110ohms 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 relay.

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

• If greater than the specified range, replace the relay.

G10 Engine Cooling Fan

1. Ignition OFF, disconnect the harness connector at the G10 engine cooling fan.

2. Connect a jumper wire between ground and the G10 ground circuit terminal 2.

3. Connect a 30 A fused jumper wire between B+ and the G10 B+ supply circuit terminal 1. The cooling fan should operate at a High speed.

• If the cooling fan does not operate, replace the G10 engine cooling fan.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)

* Engine Coolant Fan Resistor Replacement Service and Repair

* Engine Coolant Fan Replacement (LEA) Service and Repair