Cooling Fan Always On 2.0L
Diagnostic Instructions
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.
Reference Information
Schematic Reference
Engine Cooling Schematics
Connector End View Reference
Description and Operation
Cooling Fan Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- Verify that the following DTCs are not set: P0480, P0481.
- Ignition ON, verify with a scan tool that the PCM is not commanding fan activation.
- Ignition ON, observe that the fans are not activated.
Circuit/System Testing
Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
- Ignition OFF, leave the series/parallel relay in place while disconnecting the other relays.
- Ignition ON, observe that the fans are not activated.
| ⇒ | If the fans are not activated, replace the faulty relay. |
| ⇒ | If a fan is activated, test the fan voltage supply circuits for a short to voltage. |
Repair Instructions
Repair Verification
- Ignition ON, verify with a scan tool that the PCM is not commanding fan activation.
- Ignition ON, observe that the fan is not activated.
Cooling Fan Always On 2.2L
Diagnostic Instructions
Circuit/System Description
The engine cooling fan system consists of one cooling fan and one relay. The relay is powered by the battery positive voltage circuit and controlled by a switched ground from the engine control module (ECM).
During operation, the ECM supplies the ground path for the cooling fan relay through the cooling fan relay control circuit. This energizes the cooling fan relay coil, closes the relay contacts, and supplies battery positive voltage from the cooling fan
fuse through the cooling fan motor supply voltage circuit to the cooling fan. The cooling fan motor is grounded through its own ground circuit.
Reference Information
Schematic Reference
Engine Cooling Schematics
Connector End View Reference
Description and Operation
Cooling Fan Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- If DTC P0480 is set, perform that diagnostic first.
- Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
- Ignition ON, observe that the fan is not activated.
Circuit/System Testing
- Ignition OFF, disconnect the relay.
- Ignition ON, observe that the fan is not activated.
| ⇒ | If the fan is not activated, replace the relay. |
| ⇒ | If the fan is activated, test the fan voltage supply circuit for a short to voltage. |
Repair Instructions
Repair Verification
- Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
- Ignition ON, observe that the fan is not activated.
Cooling Fan Always On 2.4L
Diagnostic Instructions
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.
Reference Information
Schematic Reference
Engine Cooling Schematics
Connector End View Reference
Description and Operation
Cooling Fan Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- If DTCs P0480 or P0481 are set, then perform those diagnostics first.
- Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
- Ignition ON, observe that the fan is not activated.
Circuit/System Testing
- Ignition OFF, disconnect the relays.
- Ignition ON, observe that the fan is not activated.
| ⇒ | If the fan is not activated, replace the faulty relay. |
| ⇒ | If the fan is activated, test the fan voltage supply circuits for a short to voltage. |
Repair Instructions
Repair Verification
- Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
- Ignition ON, observe that the fan is not activated.
