Cooling Fan Inoperative 2.2L and 2.4L

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.

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

1. If DTCs 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.

1. Remove the relays.
2. Install a 30A fused jumper at the positive terminal at the battery.
3. One at a time, connect the other end of the jumper to each fan voltage supply circuit terminal at each relay connection and verify fan activation.

⇒	If the appropriate 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 does not activate and the circuits test normal, replace the fan.

4. Ignition ON, connect a 30A fused jumper between the relay switch voltage supply circuit terminal and the fan voltage supply circuit terminal at the low speed relay connection 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, test all connected components and replace as necessary.

5. Ignition ON, connect a 30A fused jumper between the relay switch voltage supply circuit terminal and the fan voltage supply circuit terminal at the high speed relay connection 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, test all connected components and replace as necessary.

6. If the circuits test normal, test and replace the faulty relay.

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.

Cooling Fan Inoperative 3.5L

The powertrain control module (PCM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. In high speed, both fans are turned ON at full speed.

In low speed operation, the PCM applies a ground to the coil side of the cooling fan 1 or low speed relay. This energizes the coil and applies voltage directly to the left or low speed cooling fan through the switch side of the relay. The left or low speed cooling fan is connected in series to the right or high speed cooling fan through the normally closed contacts of the cooling fan 3 or the cooling fan control relay. The series circuit operates both fans at low speed.

In high speed operation, the PCM applies a ground to the coil side of all three cooling fan relays. This action applies voltage directly to the right or high speed cooling fan through the switch side of the cooling fan 2 or high speed relay. Simultaneously, the cooling fan  1 or low speed relay provides voltage to the left or low speed cooling fan, while the cooling fan 3 or control relay provides a direct path to ground for the left or low speed cooling fan. With both fans connected in a parallel circuit, each fan receives full voltage and operates at high speed.

The following two tables illustrate the COOLING FAN 1 relay and the COOLING FAN 2 relay terminal locations in the underhood fuse block. The third table illustrates the COOLING FAN 3 relay terminal locations in the relay electrical connector.

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

1. Verify that the following DTCs are not set: P0480, P0481, P0691, P0692, P0693 or P0694.

⇒	If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

2. Ignition ON, command each relay ON and OFF with a scan tool. Verify that the fan turns ON and OFF with each command.
3. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions that the concern was detected.

1. Ignition OFF, disconnect the cooling fan relays.
2. Ignition ON, one at a time, verify that a test lamp illuminates between the relay switch B+ circuit and ground .

⇒	If the test lamp does not illuminate, test the relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch B+ circuit fuse is open, test all components connected to the relay switch B+ circuit and replace as necessary.

3. One at a time, connect a 30A fused jumper wire between the relay switch B+ circuit and the relay switch voltage supply circuit. Verify the fan is activated.

⇒	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, test the fan ground circuit for an open/high resistance. If the circuit tests normal, replace the fan.

4. If all circuits test normal, test or replace the appropriate cooling fan relay.

Ignition ON, command the fan relays ON and OFF with a scan tool. Verify the appropriate fan turns ON and OFF with each command.