Cooling Fan Functional Check

Diagnostic Chart:

Refer to Engine Controls Schematics. Electrical Diagrams
Refer to Engine Controls Schematics Coolant Fans. Electrical Diagrams

CIRCUIT DESCRIPTION
Power for the fan motors is supplied through the Cool Fan 1 Maxi Fuse(R) 30A and the Cool Fan 2 Maxi Fuse(R) 30A in the Underhood Accessory Wiring Junction Block. The cooling fan relays are energized when current flows from the 2 Maxifuses(R) through the relay coils to ground through the powertrain control module (PCM). The Cool Fan 1 Relay Control Circuit is grounded for low speed fans operation. The Cool Fan 1 Relay Control Circuit and the Cool Fan 2 Relay Control Circuit are both grounded for high speed fans operation.

During low speed fans operation the PCM supplies a ground path for the Cool Fan 1 Relay. This closes the Cool Fan 1 Relay contacts, allowing current to flow from the Underhood Accessory Wiring Junction Block through the relay contacts to the Engine Coolant Fan Motor 1 RH. During low speed operation, the ground path for the Engine Coolant Fan Motor 1 RH is through the Coolant Fan 1 Relay and the Engine Coolant Fan Motor 2 LH. The result is a series circuit with both cooling fans running at low speed. During high speed cooling fan operation the PCM supplies a ground path for the Cool Fan 1 Relay. The PCM also supplies a ground path for the Cool Fan Relay and the Cool Fan 2 Relay. This closes all 3 cooling fan relays. During high speed fans operation, both the Engine Coolant Fan Motor 1 RH and the Engine Coolant Fan Motor 2 LH are supplied current from the Underhood Accessory wiring Junction Block and each cooling fan has its own ground path.

TEST DESCRIPTION
The numbers below refer to numbers on the diagnostic table:
2. The PCM will enable the engine cooling fans when certain Diagnostic Trouble Codes are set. Go to applicable DTC Table first before proceeding with this table. Testing and Inspection
3. Allow engine coolant temperature to cool below 100°C (212°F) before proceeding with diagnosis.