For 1990-2009 cars

## DTC P0480 or P0481 2.0L

### 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.

### DTC Descriptors

DTC P0480: Cooling Fan Relay 1 Control Circuit
DTC P0481: Cooling Fan Relay 2 Control Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Low Speed Cooling Fan Relay Control Circuit | P0480 | P0480 | P0480 | --
Low Speed Cooling Fan Relay Coil Voltage Supply Circuit | P0480 | P0480 | P0480 | --
High Speed Cooling Fan Relay Control Circuit | P0481 | P0481 | P0481 | --
High Speed Cooling Fan Relay Coil Voltage Supply Circuit | P0481 | P0481 | P0481 | --
Series/Parallel Cooling Fan Relay Control Circuit | P0481 | P0481 | P0481 | --
Series/Parallel Cooling Fan Relay Coil Voltage Supply Circuit | P0481 | P0481 | P0481 | --

### Circuit/System Description

The powertrain control module (PCM) 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 PCM applies ground to the coil side of the low speed relay, which is relay 1. Voltage is applied directly to the left cooling fan through the switch side of the low speed relay. The right fan is connected in series to the left fan through the de-energized series/parallel relay so that both fans operate at low speed.

In high speed operation, the PCM applies a ground to the coil side of the low speed relay, the series/parallel relay, and the high speed relay, which is relay 2. Voltage is applied directly to the right cooling fan through the switch side of the high speed relay. The left cooling fan obtains voltage through the low speed relay and ground through the series/parallel relay.

When the PCM is commanding a fan relay ON, the voltage of the control circuit should be low, near 0 volts. When the PCM is commanding a fan relay OFF, the voltage of the control circuit should be high, near battery voltage. If the PCM detects that the actual voltage of the relay control circuit is different than the expected voltage, DTC P0480 or P0481 will set and the affected PCM driver will be disabled.

### Conditions for Running the DTC

• | The ignition is ON.

• | The system voltage is between 9-18 volts.

• | The relay control circuit is transitioned from OFF to ON, or ON to OFF.

### Conditions for Setting the DTC

• | An improper voltage level has been detected on the cooling fan relay control circuit.

• | The condition must be present for a minimum of 30 seconds.

### Action Taken When the DTC Sets

DTCs P0480 and P0481 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P0480 and P0481 are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Cooling Schematics

#### Connector End View Reference

• | Cooling System Component Views

• | Cooling System Connector End Views

• | Powertrain Control Module Connector End Views

#### Description and Operation

Cooling Fan Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Electrical Center Identification Views

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data Definitions

• | Scan Tool Data List

• | Scan Tool Output Controls

### Circuit/System Verification

1. Ignition ON, A/C OFF (if equipped), engine temperature below fan activation temperature of approximately 93°C (200°F) . The fans should be OFF.
2. Ignition ON, disconnect the engine coolant temperature (ECT) sensor connector. The fans should activate on high speed.
3. Connect the ECT sensor connector. Clear DTCs with a scan tool.
4. Idle the engine until the coolant reaches fan activation temperature of approximately 93°C (200°F). The fans should activate on low speed.

### Circuit/System Testing

1. Ignition OFF, disconnect the series/parallel relay.
2. Connect a 30A fused jumper between the normally-open switch contact terminals at the series/parallel relay connector in order to complete the fan ground circuit. Leave this jumper in place for the remainder of this procedure.
3. Ignition OFF, disconnect the affected relay.
4. Ignition ON, A/C OFF (if equipped), engine temperature below fan activation temperature of approximately 93°C (200°F) . Verify with a scan tool that the PCM is not commanding fan activation.
5. Ignition ON, connect a test lamp between the positive terminal at the battery and the affected relay control circuit terminal. The test lamp should not illuminate.

⇒ | If the test lamp is illuminated, test the relay control circuit for a short to ground. If the circuit tests normal, replace the PCM.

6. Ignition ON, disconnect the engine coolant temperature (ECT) sensor connector. The test lamp should illuminate.

⇒ | If the test lamp does not illuminate, test the relay control circuit for a short to voltage or an open/high resistance . If the circuit tests normal, replace the PCM.

7. Ignition ON, connect a 30A fused jumper between the positive voltage terminal at the battery and the fan voltage supply circuit terminal at the affected relay connector and verify fan activation.

⇒ | If the fan does not activate, test the fan voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the fan.

8. Ignition ON, connect a 30A fused jumper between the relay switch voltage supply circuit terminal and the fan voltage supply circuit terminal at the affected relay connector and verify fan activation.

⇒ | If the fan does not activate, test the affected relay switch voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.

9. Ignition ON, verify that a test lamp illuminates between the affected relay coil voltage supply circuit terminal and ground.

⇒ | If the test lamp does not illuminate, test the affected relay coil voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.

10. If all circuits and the PCM test normal, replace the affected relay.

### Repair Instructions

• | Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Cooling Fan and Shroud Replacement

• | Fan Shroud Replacement

• | Powertrain Control Module Replacement

## DTC P0480 or P0481 2.2L and 2.4L

### 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.

### DTC Descriptors

DTC P0480: Cooling Fan Relay 1 Control Circuit
DTC P0481: Cooling Fan Relay 2 Control Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Low Speed Cooling Fan Relay Control Circuit | P0480 | P0480 | P0480 | --
Low Speed Cooling Fan Relay Coil Voltage Supply Circuit | P0480 | P0480 | P0480 | --
High Speed Cooling Fan Relay Control Circuit | P0481 | P0481 | P0481 | --
High Speed Cooling Fan Relay Coil Voltage Supply Circuit | P0481 | P0481 | P0481 | --

### Circuit/System Description

The engine control module (ECM) grounds the low speed relay, which is relay 1, and the high speed relay, which is relay 2, control circuits through an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line that is monitored by the ECM. When the ECM is commanding a component ON, the voltage potential of the control circuit should be low, near 0 volts. When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high, near battery voltage. If the ECM detects that the actual state of the control circuit does not match the expected state, a DTC will set.

### Conditions for Running the DTC

• | The ignition is ON.

• | The system voltage is between 9-18 volts.

### Conditions for Setting the DTC

• | An improper voltage level has been detected on the cooling fan relay control circuit.

• | The condition must be present for a minimum of 30 seconds.

### Action Taken When the DTC Sets

DTCs P0480 and P0481 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P0480 and P0481 are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Cooling Schematics

#### Connector End View Reference

• | Cooling System Component Views

• | Cooling System Connector End Views

• | Engine Control Module Connector End Views for the 2.2L engine

• | Engine Control Module Connector End Views for the 2.4L engine

#### Description and Operation

Cooling Fan Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

• | Electrical Center Identification Views

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls for the 2.2L engine

• | Scan Tool Output Controls for the 2.4L engine

### Circuit/System Verification

Ignition ON, command each relay ON and OFF with a scan tool. Feel or listen to verify that each relay turns ON and OFF with each command.

### Circuit/System Testing

1. Ignition OFF, disconnect the affected relay.
2. Ignition ON, connect a test lamp between the positive terminal at the battery and the relay control circuit terminal.
3. Command the relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp is always ON, test the relay control circuit for a short to ground. If the circuit tests normal, replace the ECM.

⇒ | If the test lamp is always OFF, test the relay control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

4. Connect a 30A fused jumper wire between the positive voltage terminal at the battery and the fan voltage supply circuit terminal and verify fan activation.

⇒ | If the fan does not activate, test the fan voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the fan.

5. Ignition ON, connect a 30A fused jumper wire between the relay switch voltage supply circuit terminal and the fan voltage supply circuit terminal and verify fan activation.

⇒ | If the fan does not activate, test the relay switch voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, replace the relay.

6. Ignition ON, verify that a test lamp illuminates between the relay coil voltage supply circuit terminal and ground.

⇒ | If the test lamp does not illuminate, test the relay coil voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, replace the relay.

7. If all circuits and the ECM test normal, replace the affected relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Cooling Fan and Shroud Replacement

• | Fan Shroud Replacement

• | Engine Control Module Replacement for the 2.2L engine

• | Engine Control Module Replacement for the 2.4L engine