For 1990-2009 cars

## Cooling Fan Always On V6

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of the diagnostic category.

### Circuit/System Description

The engine control module (ECM) commands the fans ON in either high speed, medium speed, or low speed, depending on cooling requirements.

#### Low Speed

In low speed operation, the ECM applies ground to the coil side of the following relays with the cooling fan relay 1 control circuit:

• | Cooling Fan Left Low Speed Relay

• | Cooling Fan Right Low Speed Relay

• | Cooling Fan Speed Control Relay

This energizes the relay coils. The low speed cooling fan relays supply power to the appropriate cooling fan motor through an internal fan resistor. The fan speed control relay contacts close and supply a direct ground path for the left cooling fan motor. The right cooling fan motor is connected to a dedicated ground. This results in both fans operating at low speed.

#### Medium Speed

In medium speed operation, the ECM commands the low speed fan relays, and the speed control relay off. The ECM simultaneously commands both of the cooling fan high speed relays on with the cooling fan relay 2 control circuit. The cooling fan motors are supplied power directly from the cooling fan high speed relays. The right cooling fan is connected to a dedicated ground, and operates at high speed. The left cooling fan is supplied a ground through the right cooling fan resistor and fan motor, which is connected to the de-energized cooling fan speed control relay. This results in the right cooling fan operating at a reduced speed.

#### High Speed

In high speed operation, the ECM applies a ground to the coil side of all five cooling fan relays. When energized, the high speed relays apply voltage directly to the cooling fans through the switch side of the relays. The energized cooling fan speed control relay provides a direct ground circuit for the left cooling fan. This arrangement allows each fan to receive full voltage and operate at high speed.

### Reference Information

#### Schematic Reference

• | Engine Cooling Schematics

• | Electrical Center Identification Views

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Cooling Fan Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

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

⇒ | If any of the above DTCs are set refer to DTC P0480, P0481, P0691, P0692, P0693, or P0694.

2. Ignition ON, with a scan tool verify that the ECM is not commanding fan activation.
3. Ignition ON, observe that the fan is not activated.

### Circuit/System Testing

1. Ignition OFF, disconnect the appropriate cooling fan relay.
2. Ignition ON, verify that the cooling fan is not ON.

⇒ | If the fan is ON, test for a short to voltage in the relay controlled output circuit terminal 8.

3. If all circuits test normal, test or replace the cooling fan relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Relay Replacement

## Cooling Fan Always On LDK with Single Fan

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of the diagnostic category.

### Circuit/System Description

The engine cooling fan system is composed of one fan, 5 relays, the engine control module (ECM), and the associated wiring. The fan assembly includes two resistors, which enable the fan to operate at 3 speeds.

In low speed operation, the ECM provides ground to ECM terminal X2 46. The Cooling Fan Relay activates and provides ground to the coils of the Cooling Fan Medium Speed 2 Relay and the Cooling Fan Speed Control Relay. The Cooling Fan Speed Control Relay activates and provides power to the coil of the Cooling Fan High Speed Relay. The Cooling Fan High Speed Relay remains inactive because ECM terminal X2 45 is not grounded. The Cooling Fan Medium Speed 2 Relay provides power to the cooling fan motor through cooling fan terminal 2 and the internal fan resistor.

In medium speed operation, the ECM provides ground to ECM terminal X2 45. The Cooling Fan High Speed Relay remains inactive because power is not provided to the coil from the Cooling Fan Speed Control Relay. The Cooling Fan Medium Speed 1 Relay activates and provides power to the cooling fan motor through cooling fan terminal 3 and the internal fan resistor.

In high speed operation, the ECM provides ground to ECM terminals X2 45 and X2 46. As previously described, power is now provided to both cooling fan terminals 2 and 3. In addition, power and ground are now provided to the coil of the Cooling Fan High Speed Relay. The Cooling Fan High Speed Relay activates and provides power to the cooling fan motor through cooling fan terminal 4.

### Reference Information

#### Schematic Reference

• | Engine Cooling Schematics

• | Electrical Center Identification Views

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Cooling Fan Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Verify that DTCs P0480, P0481, P0691, P0692, P0693 and P0694 are not set.

⇒ | If any cooling system DTCs are set, repair the DTC first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle.

2. Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
3. Ignition ON, observe that the fan is not activated.

### Circuit/System Testing

Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the relays.
2. Ignition ON, observe that the fan is not activated.

⇒ | If the fan is not activated, then replace the faulty relay.

⇒ | If the fan is activated, then test the fan voltage supply circuits for a short to voltage.

### Repair Verification

1. Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
2. Ignition ON, observe that the fan is not activated.

## Cooling Fan Always On LCD, LBX or LBS

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### Diagnostic Fault Information

#### KR20J Cooling Fan Left High Speed Relay

Circuit | Short to Ground | High Resistance | Open | Short to voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Relay Coil Ignition Circuit | P0691 00 | P0691 00 | P0480 00 | -- | --
Relay Switch B+ Circuit | 1 | 1 | 1 | -- | --
Relay Coil Control Circuit | P0691 00 | P0691 00 | P0480 00 | P0692 00 | --
Relay Controlled Output Circuit | 1 | 1 | 1 | 2 | --

1. Low and medium speed fan inoperative without a DTC.
2. Medium speed fan always ON without a DTC.

#### KR20G Cooling Fan Left Low Speed Relay, KR20E Cooling Fan Speed Control Relay and KR20H Cooling Fan Right Low Speed Relay

Circuit | Short to Ground | High Resistance | Open | Short to voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Relay Coil Ignition Circuit | P0693 00 | P0693 00 | P0481 00 | -- | --
Relay Switch B+ Circuit | 1 | 1 | 1 | -- | --
Relay Coil Control Circuit | P0693 00 | P0693 00 | P0481 00 | P0694 00 | --
Relay Controlled Output Circuit | 1 | 1 | 1 | 2 | --

1. Fans inoperative without a DTC.
2. Medium speed fan always ON without a DTC.

#### KR20A Cooling Fan Medium Speed Relay

Circuit | Short to Ground | High Resistance | Open | Short to voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Relay Coil Ignition Circuit | P0695 00 | P0695 00 | P0482 00 | -- | --
Relay Switch B+ Circuit | 1 | 1 | 1 | -- | --
Relay Coil Control Circuit | P0695 00 | P0695 00 | P0482 00 | P0696 00 | --
Relay Controlled Output Circuit | 1 | 1 | 1 | 2 | --

1. High speed fan inoperative without a DTC.
2. High speed fan always ON without a DTC.

### Circuit/System Description

The engine control module (ECM) commands the fans ON in either high speed, medium speed, or low speed, depending on cooling requirements.

#### Low Speed

In low speed operation, the ECM applies ground to the coil side of the following relays with the cooling fan relay 1 control circuit:

• | Cooling Fan Left Low Speed Relay

• | Cooling Fan Right Low Speed Relay

• | Cooling Fan Speed Control Relay

This energizes the relay coils. The low speed cooling fan relays supply power to the appropriate cooling fan motor through an internal fan resistor. The fan speed control relay contacts close and supply a direct ground path for the left cooling fan motor. The right cooling fan motor is connected to a dedicated ground. This results in both fans operating at low speed.

#### Medium Speed

In medium speed operation, the ECM commands the low speed fan relays, and the speed control relay off. The ECM simultaneously commands both of the cooling fan high speed relays on with the cooling fan relay 2 control circuit. The cooling fan motors are supplied power directly from the cooling fan high speed relays. The right cooling fan is connected to a dedicated ground, and operates at high speed. The left cooling fan is supplied a ground through the right cooling fan resistor and fan motor, which is connected to the de-energized cooling fan speed control relay. This results in the right cooling fan operating at a reduced speed.

#### High Speed

In high speed operation, the ECM applies a ground to the coil side of all five cooling fan relays. When energized, the high speed relays apply voltage directly to the cooling fans through the switch side of the relays. The energized cooling fan speed control relay provides a direct ground circuit for the left cooling fan. This arrangement allows each fan to receive full voltage and operate at high speed.

### Reference Information

#### Schematic Reference

Engine Cooling Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Cooling Fan Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Verification

1. Ignition OFF, disconnect the appropriate cooling fan relay.

⇒ | If any of the above DTCs are set refer to Diagnostic Trouble Code (DTC) List - Vehicle

2. Ignition ON, command the appropriate fan relay ON and OFF with a scan tool. Verify that the fans turn ON and OFF when changing between the commanded states.

### Circuit/System Testing

1. Ignition OFF, disconnect the appropriate cooling fan relay.
2. Ignition ON, verify that the cooling fan is not ON.

⇒ | If the fan is ON, test for a short to voltage in the relay controlled output circuit terminal 8.

3. If all circuits test normal, test or replace the cooling fan relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | LINK 22835

• | Engine Coolant Fan Motor Replacement

## Cooling Fan Always On LDK with Dual Fans

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of the diagnostic category.

### Circuit/System Description

The engine control module (ECM) commands the fans ON in either high speed, medium speed, or low speed, depending on cooling requirements.

#### Low Speed

In low speed operation, the ECM applies ground to the coil side of the following relays with the cooling fan relay 1 control circuit:

• | Cooling Fan Left Low Speed Relay

• | Cooling Fan Right Low Speed Relay

• | Cooling Fan Speed Control Relay

This energizes the relay coils. The low speed cooling fan relays supply power to the appropriate cooling fan motor through an internal fan resistor. The fan speed control relay contacts close and supply a direct ground path for the left cooling fan motor. The right cooling fan motor is connected to a dedicated ground. This results in both fans operating at low speed.

#### Medium Speed

In medium speed operation, the ECM commands the low speed fan relays, and the speed control relay off. The ECM simultaneously commands both of the cooling fan high speed relays on with the cooling fan relay 2 control circuit. The cooling fan motors are supplied power directly from the cooling fan high speed relays. The right cooling fan is connected to a dedicated ground, and operates at high speed. The left cooling fan is supplied a ground through the right cooling fan resistor and fan motor, which is connected to the de-energized cooling fan speed control relay. This results in the left cooling fan operating at a reduced speed.

#### High Speed

In high speed operation, the ECM applies a ground to the coil side of all five cooling fan relays. When energized, the high speed relays apply voltage directly to the cooling fans through the switch side of the relays. The energized cooling fan speed control relay provides a direct ground circuit for the left cooling fan. This arrangement allows each fan to receive full voltage and operate at high speed.

### Reference Information

#### Schematic Reference

• | Engine Cooling Schematics

• | Electrical Center Identification Views

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Cooling Fan Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

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

⇒ | If any of the above DTCs are set refer to DTC P0480, P0481, P0691, P0692, P0693, or P0694.

2. Ignition ON, with a scan tool verify that the ECM is not commanding fan activation.
3. Ignition ON, observe that the fan is not activated.

### Circuit/System Testing

1. Ignition OFF, disconnect the appropriate cooling fan relay.
2. Ignition ON, verify that the cooling fan is not ON.

⇒ | If the fan is ON, test for a short to voltage in the relay controlled output circuit terminal 8.

3. If all circuits test normal, test or replace the cooling fan relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Relay Replacement