Cooling Fan Malfunction LSJ

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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. High speed has both fans turned on at a higher speed.

In low speed operation, the PCM applies ground to the coil side of the COOL/FAN Relay 1. This energizes the coil and applies voltage to the left cooling fan through the switch side of the relay, which is fed by the COOL/FAN 1 fuse. After voltage has passed through the cooling fan 1, it continues through the COOLSER/PAR Relay, which acts as a series/parallel relay, controlling fan speed, a ground path is given through G101. In low speed, the COOLSER/PAR Relay passes voltage to the cooling fan 2, effectively operating both fans in a series circuit. From the cooling fan 2, a ground path is given through G111.

In high speed operation, the PCM applies a ground to the coil side of the COOL/FAN Relay 1, COOL/FAN Relay 2, and COOLSER/PAR Relay. On the COOL/FAN Relay 2, the energized coil closes the switch side of the relay and applies voltage to the cooling fan 2. The energized COOLSER/PAR pulls the switch side over, providing a direct path to ground for the cooling fan 1, which has voltage applied through the energized COOL/FAN Relay 1. In high speed mode, the fans are operated as a parallel circuit with full voltage applied to each.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Cooling System Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

Scan Tool Reference

When checking the schematics and there is not any called out pinout numbers for the relays, or relay connector end views. When reading the diagnostics the following must be understood:

Due to the amount of diagnostic circuit call outs within the fuse block relay location and the amount of relays involved an understanding of the relay pinout circuit function locations must be understood. This vehicle carries no schematic pinout call outs per relay to make the diagnostic naming easier. Understanding is based upon circuit function naming.

1. Ignition ON, command the Fan Relay 1 low speed output control ON and OFF with a scan tool. Verify the fan low speed function turns ON and OFF with each command.

⇒	If the fan low speed does not turn ON and OFF with each command, proceed with the Low Speed Inoperative diagnostic.

⇒	If the fan low speed remains ON at all times when commanding ON and OFF, proceed with the Fans Always ON diagnostic.

2. Command the Fan Relays 1, 2 & 3 high speed output control ON and OFF with a scan tool. Verify the fan high speed function turns ON and OFF with each command.

⇒	If the fan high speed does not turn ON and OFF with each command, proceed with the High Speed Inoperative diagnostic.

⇒	If the fan high speed remains ON at all times when commanding ON and OFF, proceed with the Fans Always ON diagnostic.

Low Speed Inoperative

1. Ignition OFF, disconnect the COOL/FAN 1 Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the relay coil control circuit terminal in line with Underhood Fuse Block E10 pinout and ground.

⇒	If the test lamp illuminates, test the relay coil control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the COOL/FAN 1 Relay coil B+ circuit terminal and ground.

⇒

If the test lamp does not illuminate, test the relay coil B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the COOL/FAN 1 Relay, controlled output circuit, in line with Underhood Fuse Block C1 F10 pin side for a short to ground. If the circuit tests normal, test or replace the cooling fan 1 motor.

4. Verify that a test lamp illuminates between the COOL/FAN 1 Relay switch B+ circuit terminal and ground.

⇒	If the test lamp does not illuminate, test the relay switch B+ for a short to ground or an open/high resistance.

5. Connect a test lamp between the COOL/FAN 1 Relay coil B+ circuit terminal and the relay coil control circuit inline with underhood fuse block terminal C1 E10 side.
6. Command the Fan Relay 1 output ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always OFF, test the relay coil control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PCM.

7. Connect a 40-amp fused jumper wire between the COOL/FAN 1 Relay switch B+ circuit terminal and the COOL/FAN 1 Relay controlled output circuit terminal in line with Underhood Fuseblock C1 F10 pinout.
8. Disconnect the harness connector at the cooling fan 1 terminal 1.
9. Connect a test lamp between the Cooling Fan 1 motor supply voltage circuit terminal 1 and ground. The test lamp should illuminate.

⇒	If the test lamp does not illuminate, test the cooling fan motor supply voltage circuit for an open/high resistance. If the circuit tests normal, test or replace the COOL/FAN 1 Relay.

10. Reconnect the harness connector at the cooling fan 1 motor terminal 1.
11. Disconnect the COOL SER/PAR Relay.
12. Test for B+ between the relay controlled output circuit in line with Underhood Fuseblock C1 A6 pinout and ground.

⇒	If less than B+, test the relay controlled output circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the cooling fan 1 motor.

13. Reconnect the COOL SER/PAR Relay.
14. Disconnect the harness connector at the Cooling Fan 2 Motor.
15. Ignition OFF, test for less than 1.0 ohm of resistance between the Cooling Fan 2 Motor ground circuit. terminal 2 and ground.

⇒	If greater than 1.0 ohm, test the ground circuit for an open/high resistance.

16. Ignition ON, test for B+ between the cooling fan motor supply voltage terminal 1 and ground.

⇒	If less than B+, test the cooling fan motor supply voltage terminal 1 for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the COOL SER/PAR Relay.

17. If all circuits test normal, test or replace the Cooling Fan 2 Motor.

High Speed Inoperative

1. Ignition OFF, disconnect the COOL/FAN 2 Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the COOL/FAN 2 Relay coil control circuit terminal and ground.

⇒	If the test lamp illuminates, test the relay coil control circuit for a short to voltage.

3. Verify a test lamp illuminates between the relay coil B+ circuit and ground.

⇒

If the test lamp does not illuminate, test the relay coil B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the relay coil control circuit terminal for a short to ground. If the circuit tests normal, test or replace the COOL/FAN 2 Relay.

4. Verify that a test lamp illuminates between the relay switch B+ supply terminal and ground.

⇒	If the test lamp does not illuminate, test the COOL/FAN 2 Relay switch B+ circuit terminal for an open/high resistance.

5. Connect a test lamp between the COOL/FAN 2 Relay coil B+ circuit terminal and the relay coil control circuit terminal.
6. Command the Fan Relays 2 & 3 output ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always OFF, test the high speed cooling fan relay control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PCM.

7. Disconnect the COOL SER/PAR Relay.
8. Verify that a test lamp does not illuminate between the COOL SER/PAR Relay coil control circuit and ground.

⇒	If the test lamp illuminates, test the COOL SER/PAR Relay coil control circuit for a short to voltage.

9. Verify a test lamp illuminates between the COOL SER/PAR Relay switch B+ circuit terminal and ground.

⇒	If the test lamp does not illuminate, test the COOL SER/PAR Relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test or replace the COOL SER/PAR Relay.

10. Connect a test lamp between the COOL SER/PAR Relay switch B+ circuit terminal and the relay coil control circuit terminal.
11. Command the Fan Relays 2 & 3 output ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always OFF, test the high speed cooling fan control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PCM.

12. Ignition OFF, test for less than 1.0 ohm of resistance between the COOL SER/PAR Relay ground circuit terminal and ground. Follow G101 circuit to the relay.

⇒	If greater than 1.0 ohm, test the COOL SER/PAR Relay ground circuit for an open/high resistance.

13. Disconnect the harness connector at the Cooling Fan 2 Motor.
14. Ignition OFF, test for less than 1.0 ohm of resistance between the cooling fan 2 motor ground circuit terminal 3 and ground.

⇒	If greater than 1.0 ohm, test the ground circuit for an open/high resistance.

15. Connect the harness connector at the Cooling Fan 2 Motor.
16. Ignition ON, connect a 40-amp fused jumper wire between the COOL/FAN 2 Relay switch B+ circuit terminal and the relay controlled output circuit terminal. Verify the cooling fan high speed is activated.

⇒	If the high speed cooling fan does not activate, test the relay controlled output circuit for an open/high resistance. If the circuit tests normal, test or replace the cooling fan 2 motor.

17. If all circuits test normal, test or replace the COOL/FAN Relay 2.

Fans Always ON

1. Ignition OFF, disconnect the COOL/FAN 2 Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the relay coil B+ circuit terminal and the relay controlled output circuit terminal.

⇒	If the test lamp illuminates, test the relay controlled output circuit for a short to ground. If all circuits test normal, replace the PCM.

3. Reconnect the COOL/FAN 2 Relay.
4. Disconnect the harness connector at the cooling fan 1 motor.
5. Disconnect the COOL SER/PAR Relay.
6. Verify that a test lamp does not illuminate between the COOL SER/PAR Relay switch B+ circuit and the relay coil control circuit terminal.

⇒	If the test lamp illuminates, test the COOL SER/PAR Relay coil control circuit for a short to ground. If all circuits test normal, replace the PCM.

7. Verify that a test lamp does not illuminate between the COOL SER/PAR Relay coil control circuit terminal and ground.

⇒	If the test lamp illuminates, test the COOL SER/PAR Relay coil control circuit for a short to B+. If the circuit tests normal, replace the COOL/Fan 2 Relay.

8. Verify that a test lamp does not illuminate between the relay controlled output circuit and ground.

⇒	If the test light illuminates, test the relay controlled output circuit for a short to B+.

9. Disconnect the COOL/FAN 1 Relay.
10. Verify that a test lamp does not illuminate between the COOL/FAN 1 Relay coil B+ circuit terminal and the relay coil control circuit terminal.

⇒	If the test lamp illuminates, test the COOL/FAN 1 Relay coil control circuit for a short to ground. If all circuits test normal, replace the PCM.

11. Verify a test lamp does not illuminate between the COOL/FAN 1 Relay controlled output circuit terminal and ground.

⇒	If the test lamp illuminates, test the COOL/FAN 1 Relay controlled output circuit for a short to B+.

12. If all circuits test normal, test or replace the COOL/FAN 1 Relay.

1. Ignition OFF, disconnect the affected relay.
2. Test for 60-180 ohms of resistance between terminals 85 and 86.

⇒	If the resistance is not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If less than infinite, replace the relay.

4. Install a 20-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2.0 ohms of resistance between terminals 30 and 87.

⇒	If greater than 2.0 ohms, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Cooling Fan Malfunction LE5

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

The engine control module (ECM) commands the fan on in either high speed or low speed, depending on cooling requirements. In low speed, the fan is turned on at a reduced speed. High speed has the fan turned on at a higher speed.

In low speed operation, the ECM applies ground to the coil side of the COOL/FAN Relay 1. This energizes the coil and applies voltage to the low speed windings of the fan through the switch side of the COOL/FAN Relay 1, which is fed by the COOL/FAN 1 fuse 30A. In low speed, the COOL /FAN 1Relay passes voltage to the Cooling Fan Motor Low Speed Winding. From the Cooling Fan Motor, a ground path is given through G111.

In high speed operation, the ECM applies a ground to the coil side of the COOL/FAN 2 Relay, and COOL/FAN 1 Relay. On the COOL/FAN 2 Relay, the energized coil closes the switch side of the relay and applies voltage to the Cooling Fan Motor High Speed Winding. From the Cooling Fan Motor, a ground path is given through S110 and then G111.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Cooling System Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

Scan Tool Reference

When checking the schematics and there is not any called out pinout numbers for the relays, or relay connector end views. When reading the diagnostics the following must be understood:

Due to the amount of diagnostic circuit call outs within the fuse block relay location and the amount of relays involved an understanding of the relay pinout circuit function locations must be understood. This vehicle carries no schematic pinout call outs per relay to make the diagnostic naming easier. Understanding is based upon circuit function naming.

1. Ignition ON, command the Fan 1 Relay output control ON and OFF with a scan tool. Verify the fan low speed function turns ON and OFF with each command.

⇒	If the fan low speed does not turn ON and OFF with each command, proceed with the Low Speed Inoperative diagnostic.

⇒	If the fan low speed remains ON at all times when commanding ON and OFF, proceed with the Fans Always ON diagnostic.

2. Command the Fan Relays 1, & 2 output control ON and OFF with a scan tool. Verify the fan high speed function turns ON and OFF with each command.

⇒	If the fan high speed does not turn ON and OFF with each command, proceed with the High Speed Inoperative diagnostic.

⇒	If the fan high speed remains ON at all times when commanding ON and OFF, proceed with the Fans Always ON diagnostic.

Low Speed Inoperative

1. Ignition OFF, disconnect the COOL/FAN 1 Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the relay coil control circuit terminal located in line with Underhood fuseblock pinout E10 side of relay and ground.

⇒	If the test lamp illuminates, test the relay coil control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the COOL/FAN 1 Relay coil B+ circuit terminal and ground.

⇒

If the test lamp does not illuminate, test the coil B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the COOL/FAN 1 Relay controlled output circuit terminal, inline with the F10 side of the Underhood fuse block for a short to ground. If the circuit tests normal, test or replace the cooling fan motor.

4. Verify that a test lamp illuminates between the COOL/FAN 1 Relay switch B+ circuit terminal and ground.

⇒	If the test lamp does not illuminate, test the relay switch B+ for a short to ground or an open/high resistance.

5. Connect a test lamp between the COOL/FAN 1 Relay switch B+ circuit terminal and the relay coil control circuit terminal in line with the Underhood fuse block pinout E10.
6. Command the Fan 1 Relay output ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always OFF, test the Low Speed Cooling Fan Relay control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

7. Connect a 40-amp fused jumper wire between the COOL/FAN 1 Relay switch B+ circuit terminal and the COOL/FAN 1 Relay controlled output circuit terminal.
8. Disconnect the harness connector at the Low Speed Winding of the Cooling Fan Motor terminal 1.
9. Connect a test lamp between the Cooling Fan supply voltage circuit terminal 1 and ground. The test lamp should illuminate.

⇒	If the test lamp does not illuminate, test the supply voltage circuit for an open/high resistance. If the circuit tests normal, test or replace the COOL/FAN 1 Relay.

10. Reconnect the harness connector at the cooling fan motor terminal 1 low speed winding circuit.
11. Disconnect the harness connector at the Cooling Fan Motor ground circuit terminal 3.
12. Ignition OFF, test for less than 1.0 ohm of resistance between the cooling fan ground circuit terminal 3 and ground.

⇒	If greater than 1.0 ohm, test the ground circuit for an open/high resistance.

13. Ignition ON, test for B+ between the cooling fan motor supply voltage circuit terminal 1 and ground.

⇒	If less than B+, test the cooling fan motor supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the COOL/FAN 1 Relay.

14. If all circuits test normal, test or replace the Cooling Fan Motor.

High Speed Inoperative

1. Ignition OFF, disconnect the COOL/FAN 2 Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the COOL/FAN 2 Relay coil control circuit terminal and ground.

⇒	If the test lamp illuminates, test the relay coil control circuit for a short to voltage.

3. Verify a test lamp illuminates between the relay coil B+ circuit terminal and ground.

⇒

If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the relay controlled output circuit terminal for a short to ground. If the circuit tests normal, test or replace the COOL/FAN 2 Relay.

4. Verify that a test lamp illuminates between the relay switch B+ terminal and ground.

⇒	If the test lamp does not illuminate, test the COOL/FAN 2 Relay switch B+ for an open/high resistance.

5. Connect a test lamp between the COOL/FAN 2 Relay coil B+ circuit terminal and the relay coil control circuit terminal.
6. Command the Fan Relays 2 & 3 output ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always OFF, test the High Speed Relay control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

7. Disconnect the harness connector at the Cooling Fan Motor High Speed Windings terminal 2.
8. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal 3 and ground.

⇒	If greater than 1.0 ohm, test the ground circuit for an open/high resistance.

9. Connect the high speed winding harness connector terminal 2 at the Cooling Fan Motor.
10. Ignition ON, connect a 40-amp fused jumper wire between the COOL/FAN 2 Relay switch B+ circuit terminal and the relay controlled output circuit terminal. Verify the high speed cooling fan circuit is activated.

⇒	If the high speed cooling fan does not activate, test the relay controlled output circuit for an open/high resistance. If the circuit tests normal, test or replace the cooling fan motor.

11. If all circuits test normal, test or replace the COOL/FAN 2 Relay.

Fans Always ON

1. Ignition OFF, disconnect the COOL/FAN 2 Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the relay coil B+ circuit terminal and the relay controlled output circuit terminal.

⇒	If the test lamp illuminates, test the relay controlled output circuit for a short to ground. If all circuits test normal, replace the ECM.

3. Reconnect the COOL/FAN 2 Relay.
4. Disconnect the harness connector at the cooling fan motor.
5. Disconnect the COOL/FAN 1 Relay.
6. Verify that a test lamp does not illuminate between the COOL/FAN 1 Relay switch B+ circuit terminal and the relay coil control circuit.

⇒	If the test lamp illuminates, test the COOL/FAN 1 Relay controlled output circuit for a short to ground. If all circuits test normal, replace the ECM.

7. Verify a test lamp does not illuminate between the COOL/FAN 1 Relay controlled output circuit terminal and ground.

⇒	If the test lamp illuminates, test the COOL/FAN 1 Relay output controlled circuit for a short to B+.

8. If all circuits test normal, test or replace the COOL/FAN 1 Relay.

1. Ignition OFF, disconnect the affected relay.
2. Test for 60-180 ohms of resistance between terminals 85 and 86.

⇒	If the resistance is not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If less than infinite, replace the relay.

4. Install a 20-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2.0 ohms of resistance between terminals 30 and 87.

⇒	If greater than 2.0 ohms, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.