Cooling Fan Always On

Cooling Fan Always On (2.0L)

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. 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. 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.


Circuit/System Verification

1. Verify that the following DTC's are not set: P0480, P0481.

^ If any of the DTC's are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions

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

Circuit/System Testing

1. Ignition OFF, disconnect the relays.
2. 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

* Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Cooling Fan and Shroud Replacement (2.0L (LSJ)) Cooling Fan and Shroud Replacement (2.2L (L61), 2.4L (LE5))
* Fan Shroud Replacement
* Powertrain Control Module Replacement

Repair Verification

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