Cruze

Cooling Fan Inoperative - LLW

The engine control module (ECM) controls cooling fan operation in either high speed or low speed mode, depending on cooling requirements. To activate a fan, the ECM applies ground to the coil side of the applicable fan relay. This energizes the coil and applies voltage directly to the cooling fan through the switch side of the relay.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the DTC information with a scan tool. Verify that DTCs P0480, P0481 or P0482 are not set.

⇒	If any of the above DTCs are set, refer to DTC P0480, P0481, or P0482 .

2. Command the cooling fan relays ON and OFF with a scan tool. The cooling fans should operate with the appropriate commands.
3. Command the appropriate fan relay ON and OFF with a scan tool. Verify that the fans turn ON and OFF when changing between the commanded states.

1. Ignition OFF, disconnect the cooling fan relays.
2. Connect a 30 A fused jumper between the relay switch circuit terminal 30 and the ground circuit terminal 87 at the series/parallel fan control relay connector. This will complete the main fan ground circuit. Leave this jumper in place for the remainder of this procedure.

Note: The following test must be performed on both the high speed fan relay circuit and the low speed fan relay circuit.

3. Ignition ON, verify that a test lamp illuminates between the relay switch B+ circuit terminal 30 and ground.

⇒

If the test lamp does not illuminate, test the appropriate 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 the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the relay.

Note: The following test must be performed first on the high speed fan relay circuit and next on the low speed fan relay circuit. Leave the jumper connected to the low speed fan relay circuit for the next test.

4. Install the fan control relay. Verify both fans activate at low speed.

⇒	If both fans do not activate, test the relay controlled output circuit terminal 87A of the fan control relay for a short to ground or an open/high resistance.

5. If all circuits test normal, test or replace the relay.

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not the specified range, replace the relay.

Static Test

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 Ω between terminals 85 and 86.
3. Install the fan control relay. Verify both fans activate at low speed.

⇒	If both fans do not activate, test the relay controlled output circuit terminal 87A of the fan control relay for a short to ground or an open/high resistance.

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not the specified range, replace the relay.

4. Test for less than 2 Ω between the relay terminals 30 and 87A.

⇒	If greater than the specified range, replace the relay.

5. Install a 20 A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between the relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.

⇒	If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Engine Coolant Fan Replacement