Overheating Help! | Testing Cooling Fans - Relays - Connections

Summary

This video provides a comprehensive guide on troubleshooting cooling fan issues in late-model vehicles. It covers testing both low and high-speed fan functions, diagnosing power and continuity problems, and testing the fan motor, relays, and wiring. The steps include using a multimeter to check voltage, continuity, and relay activation. The guide also explores how to test the fan motor by applying direct power. Whether you're dealing with a malfunctioning cooling fan or overheating issues, this tutorial offers clear, step-by-step instructions to pinpoint and solve the problem.

Takeaways

• 😀 Start by checking the vehicle's cooling fan operation with the air conditioning turned on; the low-speed fan should activate immediately.
• 😀 If the fan doesn't turn on, check for power at the fan relay using a multimeter to ensure 12V DC is reaching the relay.
• 😀 If there’s no 12V power at the relay, investigate the connection between the relay and the battery for any wiring issues or shorts.
• 😀 Test the continuity of the wiring between the relay and the fan harness connectors to ensure there are no breaks in the wiring.
• 😀 If continuity is present, the wiring is intact; if not, locate and fix the break between the relay and the harness connector.
• 😀 Test the fan relay by applying 12V to terminals 1 and 2 and check for continuity between terminals 3 and 5 when the relay is activated.
• 😀 Directly apply 12V to the fan motor using a battery or power pack to test the fan itself and verify if it's working.
• 😀 For high-speed fan operation, you can simulate a coolant temperature sensor signal using a 150-ohm resistor to trigger the high-speed fan.
• 😀 Alternatively, apply 12V directly to the top and bottom terminals of the fan motor to test its high-speed function.
• 😀 Ensure to check all connections and components systematically to identify whether the problem lies in the relay, wiring, or the fan motor itself.
• 😀 If all tests are passed, the cooling system is functioning correctly; replace any faulty relays or motors if necessary to resolve fan issues.

Q & A

What is the first step in diagnosing a cooling fan issue in a vehicle?

The first step is to start the vehicle and turn on the air conditioning. If the fans are working correctly, the low-speed fan should activate.

What tool is necessary to test the power going to the fan relay?

A multimeter is required to test the power going to the fan relay and verify that 12 volts of power is being supplied.

What should you do if the cooling fans do not turn on after starting the vehicle and air conditioning?

If the fans do not turn on, check the power supply to the relay by using a multimeter to test for 12 volts at the relay terminals.

What is the purpose of checking the relay when troubleshooting the cooling fan system?

Checking the relay ensures that it is functioning correctly. The relay is responsible for turning the fan on and off when the system is triggered by the air conditioning or temperature sensor.

How can you test the relay functionality?

You can test the relay by applying 12 volts to terminals 1 and 2 and checking for continuity between terminals 3 and 5, which indicates that the relay is working.

What does continuity testing of the wiring harness help identify?

Continuity testing helps identify any breaks or faults in the wiring between the relay and the cooling fan, ensuring that the electrical connection is intact.

How can you test the cooling fan motor directly?

To test the cooling fan motor, you can apply 12V power directly to the motor's connector. If the fan operates correctly, it confirms that the motor is functional.

What is the difference between testing the low-speed and high-speed fan functions?

Testing the low-speed fan involves checking the relay and wiring. For the high-speed fan, you can either manipulate the coolant temperature sensor or apply power directly to specific terminals on the relay.

How do you verify the high-speed fan operation when testing the fan directly?

To verify the high-speed operation, apply 12V power to both the top terminals and both bottom terminals of the fan relay. The fan should operate faster than in the low-speed test.

What should be done if continuity is not detected during the wiring check?

If continuity is not detected, you need to locate the break in the wiring between the relay and the cooling fan motor, as the issue lies in the electrical connection.