Chevrolet Trax: Cooling fan always ON (2H0)

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 provide an overview of each diagnostic category.

Circuit/System Description

The engine cooling fan system consists of a cooling fan assembly containing one electric cooling fan. The engine control module (ECM) uses two fan control circuits and a series of two relays to command the fans ON in either high speed or low speed, depending on cooling requirements. The ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. Each driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. In low speed, the fan is turned ON at a reduced speed. High speed has the fan turned ON at full speed.

Diagnostic Aids

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

• Cooling Fan Relay 1 operates both fans at a low speed
• Cooling Fan Relay 2 operates one fan at a high speed

• Certain resistance conditions with IAT or ECT sensors may cause unwarranted cooling fan activation. If the ECM is commanding the cooling fans ON for no apparent reason and without any component or system DTCs set, the IAT or ECT sensor may be skewed. If this condition is suspected, refer to the temperature versus resistance tables in the appropriate Engine Controls subsection.

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 (2H0)

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 or P0481 is not set.

• If any of the DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

• If none of the DTCs are set

3. Verify the scan tool parameters listed below display OFF:

• Cooling Fan Relay 1 Command
• Cooling Fan Relays 2 Command
• If a scan tool parameter displays ON

Refer to Diagnostic Aids and Symptoms - Engine Cooling for further diagnosis.

• If both scan tool parameters display OFF

4. Verify that the fan is not activated.

• If a fan is operating

Refer to Circuit/System Testing.

• If the fan is OFF

5. All OK.

Circuit/System Testing

Cooling Fan Always ON

1. Ignition OFF, disconnect the KR20C Cooling Fan Low Speed Relay and KR20D Cooling Fan High Speed Relay one at a time, ignition ON.
2. Verify that the cooling fan is OFF.

• If the cooling fan is ON after both relays are removed

1. Ignition OFF, disconnect the harness connector at the G10 Cooling Fan Motor, ignition ON.
2. Test for less than 1 V between the appropriate output control circuit terminal 87 and ground.

• If 1 V or greater, repair the short to voltage in the circuit.
• If the cooling fan is OFF after both relays are removed

3. Test or replace the appropriate cooling fan relay.

Component Testing

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 70 ohms or greater than 110 ohms

Replace the cooling fan relay.

• If between 70-110 ohms

4. Test for infinite resistance between 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.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Relay Replacement (Within an Electrical Center) , Relay Replacement (Attached to Wire Harness)

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