Cooling Fan Always On

Cooling Fan Always On (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 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 operates the fan at a high speed

* Certain resistance conditions with IAT or ECT sensors may cause unwarranted cooling fan activation. If the ECM is commanding the cooling fans ON for no apparent reason and without any component or system DTCs set, the IAT or ECT sensor may be skewed. If this condition is suspected, refer to the temperature versus resistance tables listed below.

- Temperature Versus Resistance (Engine Coolant Temperature Sensor) Temperature Versus Resistance (Engine Coolant Temperature Sensor)

- Temperature Versus Resistance - Intake Air Temperature Sensor (Hitachi Sensor) Temperature Versus Resistance - Intake Air Temperature Sensor (Hitachi Sensor)

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 Fuse Block - Underhood Label

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 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, 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. Ignition ON, observe the scan tool parameters listed below. Verify that both parameters display OFF.

* Cooling Fan Relay 1 Command

* Cooling Fan Relays 2 Command

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 fan is 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 fan is 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 ohms between terminals 85 and 86.

• If not within the specified range, replace the KR20 Cooling Fan Relay.

3. Test for infinite resistance between the terminals listed below:

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