Chevrolet Trax: Cooling fan inoperative (LUJ OR LUV)

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The engine cooling fan system is composed of one cooling fan, a series of 5 relays, the engine control module (ECM), and the associated wiring. The cooling fan assembly includes two resistors. This combination of components enables the ECM to operate the cooling fan at 3 speeds using two fan control circuits.

Diagnostic Aids

• The scan tool cooling fan output control operates as follows:

• Cooling Fan Relay 1 operates the fan at a low speed
• Cooling Fan Relay 2 and 3 operates the fan at a medium speed
• Cooling Fan Relay 1, 2 and 3 operates the fan at a high speed

• When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion. Test the mating electrical terminals for tightness.

Reference Information

Schematic Reference

Engine Heating/Cooling Schematics (Encore), Engine Heating/Cooling Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Electrical Information Reference

• Electrical Center Identification Views (Encore) , Electrical Center Identification Views (Trax)

Description and Operation

Cooling Fan Description and Operation (LUJ or LUV)

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.
2. Verify that DTC P0480, P0481, P0691, P0692, P0693, or P0694 is not set.

• If a DTC is set

Refer to DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LUJ or LUV).

• If no DTC is set

3. Verify that the G10 Cooling Fan Motor operates at low, medium, and high speed, when commanding the appropriate cooling fan relays ON and OFF with a scan tool.

• If the cooling fan does not operate at all speeds

Refer to Circuit/System Testing.

• If the cooling fan operates at all speeds

4. All OK.

Circuit/System Testing

Inoperative in All Speeds

1. Ignition OFF, disconnect the harness connector at the R10 Cooling Fan Resistor.
2. Verify a test lamp illuminates between the ground circuit terminal 1 and B+.

• If the test lamp does not illuminate

1. Ignition OFF, remove the test lamp.
2. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If the test lamp illuminates

3. Test or replace the G10 Cooling Fan Motor. Replace the cooling fan fuses if necessary.

Low, Medium, or High Speed Inoperative

1. Ignition OFF.
2. Disconnect the following cooling fan relays, ignition ON:

• KR20C Cooling Fan Low Speed Relay
• KR20D Cooling Fan High Speed Relay
• KR20E Cooling Fan Speed Control Relay
• KR20F Cooling Fan Relay
• KR20P Cooling Fan Medium Speed Relay

3. Verify a test lamp illuminates between ground and each of the cooling fan relay B+ circuit terminals listed below:

• KR20C Cooling Fan Low Speed Relay terminal 30/3
• KR20D Cooling Fan High Speed Relay terminal 30/3
• KR20P Cooling Fan Medium Speed Relay terminal 30/3
• If the test lamp does not illuminate and the circuit fuse is good

1. Ignition OFF, remove the test lamp.
2. Test for less than 2 ohms in the appropriate relay B+ circuit, end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open

1. Ignition OFF, disconnect the harness connector at the R10 Cooling Fan Resistor.
2. Test for infinite resistance between the appropriate relay controlled output circuit terminal listed below and ground:

• KR20C Cooling Fan Low Speed Relay terminal 87/5
• KR20D Cooling Fan High Speed Relay terminal 87/5
• KR20P Cooling Fan Medium Speed Relay terminal 87/5
• If less than infinite resistance, repair the short to ground in the circuit.
• If infinite resistance, test or replace the G10 Cooling Fan Motor, replace the fuse as necessary.
• If the test lamp illuminates

4. Verify a test lamp illuminates between the KR20F Cooling Fan Relay output circuit terminal 87/5 and B+.

• If the test lamp does not illuminate

1. Ignition OFF, remove the test lamp.
2. Test for less than 2 ohms in the ground circuit, end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If the test lamp illuminates

5. Ignition OFF, Install the KR20F Cooling Fan Relay, ignition ON.
6. Verify a test lamp illuminates between each of the cooling fan relay ignition circuit terminals listed below and ground:

• KR20C Cooling Fan Low Speed Relay terminal 86/1
• KR20E Cooling Fan Speed Control Relay terminal 85/2 and 30/3
• If the test lamp does not illuminate at each terminal

1. Ignition OFF, remove the test lamp.
2. Test for less than 2 ohms between the appropriate relay ignition circuit terminal and the fuse.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp illuminates at each terminal

7. Command the cooling fan ON at low speed with a scan tool.
8. Verify a test lamp illuminates between B+ and each of the relay control circuit terminals listed below:

• KR20C Cooling Fan Low Speed Relay terminal 85
• KR20E Cooling Fan Speed Control Relay terminal 86
• If the test lamp does not illuminate

1. Ignition OFF, remove the test lamp and disconnect the KR20F Cooling Fan Relay.
2. Test for less than 2 ohms between the KR20F Cooling Fan Relay terminal 30/3 and the relay control circuit terminals listed below:

• KR20C Cooling Fan Low Speed Relay terminal 85
• KR20E Cooling Fan Speed Control Relay terminal 86
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the KR20F Cooling Fan Relay.
• If the test lamp illuminates

9. Ignition OFF, install the KR20E Cooling Fan Speed Control Relay, ignition ON.
10.  Command the cooling fan ON at low speed with a scan tool.
11.  Verify a test lamp illuminates between the KR20D Cooling Fan High Speed Relay ignition circuit terminal 85/1 and ground.

If the test lamp does not illuminate

1. Ignition OFF, remove the test lamp and disconnect the KR20E Cooling Fan Speed Control Relay.
2. Test for less than 2 ohms between the KR20D Cooling Fan High Speed Relay terminal 85/1 and KR20E Cooling Fan Speed Control Relay terminal 87/5.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the KR20E Cooling Fan Speed Control Relay.
• If the test lamp illuminates

12. Ignition OFF, install all of the previously removed cooling fan relays. Disconnect the harness connector at the R10 Cooling Fan Resistor, ignition ON.
13. Command the cooling fan ON at high speed with a scan tool.
14. Verify a test lamp illuminates between ground and each of the R10 Cooling Fan Resistor circuit terminals listed below:

• R10 Cooling Fan Resistor low speed circuit terminal 2
• R10 Cooling Fan Resistor medium speed circuit terminal 3
• R10 Cooling Fan Resistor high speed circuit terminal 4
• If the test lamp does not illuminate at each terminal

1. Ignition OFF, remove the test lamp.
2. Disconnect the appropriate relay from the list below:

• KR20C Cooling Fan Low Speed Relay
• KR20D Cooling Fan High Speed Relay
• KR20P Cooling Fan Medium Speed Relay

3. Test for less than 2 ohms in the relay controlled output circuit, end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, test or replace the relay.
• If the test lamp illuminates at each terminal

15. Test or replace the G10 Cooling Fan Motor.

Component Testing

Relay Test

1. Ignition OFF.
2. Disconnect a cooling fan relay.
3. Test for 70-110 ohms between terminals 85/2 and 86/1.

• If less than or greater than the specified range

Replace the cooling fan relay.

• If within the specified range

4. Test for infinite resistance between the following terminals:

• 30/3 and 86/1
• 30/3 and 87/5
• 30/3 and 85/2
• 85/2 and 87/5
• If less than infinite resistance

Replace the cooling fan relay.

• If infinite resistance

5. Install a 20 A fused jumper wire between relay terminal 85/2 and 12 V.
6. Install a jumper wire between relay terminal 86/1 and ground.
7. Test for less than 2 ohms between terminals 30/3 and 87/5.

• If 2 ohms or greater

Replace the cooling fan relay.

• If less than 2 ohms

8. All OK.

Cooling Fan Motor Test

1. Ignition OFF.
2. Disconnect the harness connector at the R10 Cooling Fan Resistor.
3. Connect a jumper wire between the R10 Cooling Fan Resistor terminal 1 and ground.
4. Connect an appropriately fused jumper wire between a R10 Cooling Fan Resistor terminal listed below and B+.

• R10 Cooling Fan Resistor low speed terminal 2
• R10 Cooling Fan Resistor medium speed terminal 3
• R10 Cooling Fan Resistor high speed terminal 4

5. Verify the G10 Cooling Fan Motor operates when voltage is applied to each terminal.

• The cooling fan does not operate

Replace the G10 Cooling Fan Motor.

• The cooling fan operates

6. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• Relay Replacement (Within an Electrical Center) , Relay Replacement (Attached to Wire Harness)
• Front Compartment Fuse Block Replacement
• Engine Coolant Fan Replacement (LUJ, LUV)

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