For 1990-2009 cars

## DTC P0480 or P0481 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: Low Speed Cooling Fan Relay Control Circuit
DTC P0481: High Speed Cooling Fan Relay 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

• | DTC P0480 is a Type B DTC.

• | DTC P0481 is a Type B DTC.

### Conditions for Clearing the DTC

• | DTC P0480 is a Type B DTC.

• | DTC P0481 is a Type B DTC.

### 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

#### 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

### 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 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 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 all circuits test normal, 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

Cooling Fan and Shroud Replacement

### Repair Verification

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