Cooling Fan Inoperative

Cooling Fan Inoperative (2.2L and 2.4L)

Circuit/System Description

The engine control module (ECM) grounds the cooling fan relay 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.


Circuit/System Verification

1. If DTC's P0480 or P0481 are set, then perform those diagnostics first.
2. Ignition ON, command each relay ON and OFF with a scan tool. Observe to verify that the fan turns ON and OFF with each command.

Circuit/System Testing

1. Ignition OFF, disconnect the affected relay.
2. 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, test the fan ground circuit for an open/high resistance. If the fan did not activate and the circuits test normal, replace the fan.

3. 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 it's fuse is open, test all connected components and replace as necessary.

4. If the fan and all circuits test normal, replace the relay.

Repair Instructions

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

Repair Verification

Ignition ON, command each relay ON and OFF with a scan tool. Observe to verify that each fan turns ON and OFF with each command.