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Cooling Fan Always On - LNP

The engine control module (ECM) commands the fans ON in either high speed, medium speed, or low speed, depending on cooling requirements.

Low Speed

In low speed operation, the ECM commands the low speed fan relay on. This energises the relay coil. The low speed cooling fan relay supply power directly to the right cooling fan motor. The earth circuit of the right cooling fan motor is connected to the left cooling fan motor through the cooling fan speed control 2 relay. Both cooling fan motors are running slowly.

Medium Speed

In medium speed operation, the ECM applies earth to the coil side of the cooling fan left medium speed relay, the cooling fan right medium speed relay and the cooling fan speed control 2 relay. This energizes the relay coils. The medium speed cooling fan relays supply power to the left cooling fan motor and the right cooling fan motor through internal fan resistors. The cooling fan speed control 2 relay supplies earth to the right cooling fan motor. Both cooling fan motors are running with medium speed.

High Speed

In high speed operation, the ECM applies ground to the coil side of the cooling fan high speed relay. When energised, the high speed relay applies voltage directly to the left cooling fan motor. The left cooling fan motor is running with maximum speed.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling System Description and Operation : 2.0L Diesel LNP → LDE, LLU, LXV, 2H0 LUW and LFH

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, verify that DTCs P0480, P0481, P0482, P0691, P0692, P0693, P0694, P0695, or P0696 are not set.

⇒	If any of the above DTCs are set, refer to DTC P0480-P0482 or P0691-P0696 : LNP or LNQ .

2. Verify that DTCs P0116, P0117, P0118, or P0119 are not set.

⇒	If any of the above DTCs are set, refer to DTC P0116-P0119 : LNP or LNQ .

3. Verify the cooling fan motors are not running.

⇒	If both cooling fans are running, refer to Both Cooling Fans Always Running.

⇒	If the left cooling fan is running, refer to Left Cooling Fan Always Running.

4. Command the cooling fan relay 1 ON and OFF with a scan tool. The cooling fans should operate on low speed when commanded ON, and turn OFF when commanded OFF.
5. Command the cooling fan relay 2 ON and OFF with a scan tool. The cooling fans should operate on medium speed when commanded ON, and turn OFF when commanded OFF.
6. Command the cooling fan relay 3 ON and OFF with a scan tool. The left cooling fan should operate on maximum speed when commanded ON, and turn OFF when commanded OFF.

Both Cooling Fans Always Running

1. Ignition OFF, disconnect the KR20C Cooling Fan Low Speed Relay and the KR20N Cooling Fan Right Medium Speed Relay.
2. Ignition ON, verify that both cooling fans are not operating.

⇒	If the cooling fans are running, test the controlled output circuits listed below for a short to voltage:

•	G10R Cooling Fan Motor - Right terminal A

•	G10R Cooling Fan Motor - Right terminal B

3. Ignition OFF, connect the KR20C Cooling Fan Low Speed Relay.
4. Ignition ON, verify that both cooling fans are not operating.

⇒	If the cooling fans are running, replace the KR20C Cooling Fan Low Speed Relay.

5. If all circuits test normal, replace the KR20N Cooling Fan Right Medium Speed Relay.

Left Cooling Fan Always Running

1. Ignition OFF, disconnect the KR20D Cooling Fan High Speed Relay, KR20M Cooling Fan Left Medium Speed Relay and KR20L Cooling Fan Speed Control 2 Relay.
2. Ignition ON, verify that the left cooling fan is not operating.

⇒	If the left cooling fan is running, test the controlled output circuits listed below for a short to voltage:

•	G10L Cooling Fan Motor - Left terminal A

•	G10L Cooling Fan Motor - Left terminal B

3. Ignition OFF, connect the KR20L Cooling Fan Speed Control 2 Relay.
4. Ignition ON, verify that the left cooling fan is not operating.

⇒	If the left cooling fan is running, test the controlled output circuit terminal 30 at the KR20L Cooling Fan Speed Control 2 Relay a short to voltage. If the circuit tests normal, replace the KR20L Cooling Fan Speed Control 2 Relay.

5. Ignition OFF, connect the KR20M Cooling Fan Left Medium Speed Relay.
6. Ignition ON, verify that the left cooling fan is not operating.

⇒	If the left cooling fan is running, replace the KR20M Cooling Fan Left Medium Speed Relay.

7. If all circuits test normal, replace the KR20D Cooling Fan High Speed Relay.

Static Test

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 Ω between terminals 85 and 86.

⇒	If 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 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.