How to Bypass Cooling Fan Relay

Maintaining optimal engine temperature is crucial for the efficient functioning of any vehicle. Cooling fan relays play a vital role in controlling the cooling system by regulating the operation of the cooling fans. However, there are situations where bypassing the cooling fan relay becomes necessary.

Whether you’re faced with a faulty relay or need to override it temporarily for testing purposes, understanding how to bypass the cooling fan relay can prove invaluable. In this blog post, we will delve into the process of bypassing cooling fan relays, ensuring you have the knowledge and skills to tackle this task effectively.

Step by Step Guide on How to Bypass Cooling Fan Relay

  1. Understanding the Cooling Fan Relay:

To comprehend how to bypass the cooling fan relay, it’s important to first understand its purpose. The cooling fan relay is an electrical device that controls the operation of the cooling fan(s) in a vehicle’s cooling system. It receives signals from various sources such as coolant temperature sensors or the engine control unit (ECU), and triggers the fan(s) accordingly. By bypassing this relay, you essentially take control of the fan(s) manually.

2. Safety First:

Before attempting any bypassing procedure, it is essential to prioritize safety. Always ensure the engine is turned off and the key is removed from the ignition. Take precautions to prevent accidental starting of the engine during the process. Additionally, disconnect the battery to avoid electrical mishaps.

3. Identifying the Cooling Fan Relay:

The cooling fan relay is typically located in the engine compartment fuse box or near the radiator. Refer to the vehicle’s manual or conduct an online search to determine the specific location of the relay in your car.

4. Locating the Appropriate Wires:

Once you have identified the cooling fan relay, locate the wires connected to it. There are generally two wires: one that supplies power from the battery or fuse box and another that connects to the cooling fan(s). Often, the power wire is connected to a fused source, while the other wire connects to a ground or the ECU.

5. Bypassing the Cooling Fan Relay:

To bypass the cooling fan relay, you can use a jumper wire or a fused wire.

Follow these steps:

  • Disconnect the power wire from the cooling fan relay. This is the wire that supplies power from the battery or fuse box.
  • Connect the power wire directly to the wire that leads to the cooling fan(s). This can be done using a jumper wire with alligator clips or by splicing the wires together.
  • If using a jumper wire, ensure it is securely attached to the wires and doesn’t interfere with any other components or moving parts.
  • In case you have a fused wire, ensure the appropriate fuse rating matches the requirements of the cooling fan(s) and insert it in line with the power wire.

6. Testing and Monitoring:

With the bypass in place, turn on the ignition and monitor the cooling fan(s) to ensure they are operating as intended. Keep an eye on the engine temperature gauge to ensure it remains within the optimal range.

7. Temporary Bypass Only:

It is important to note that bypassing the cooling fan relay should only be done temporarily or for diagnostic purposes. The relay serves as a safety feature that protects the engine from overheating by responding to signals from various sensors. Regular operation of the cooling fan relay should be restored once the underlying issue is resolved.

How to Jump Cooling Fan Relay

When your car’s engine is running, the cooling fan relay provides power to the cooling fan. If the relay fails, the fan will not operate and your engine will overheat. Here’s how to jump the cooling fan relay to get your engine cooled down

How to Bypass Cooling Fan Relay


Can You Manually Turn on Radiator Fan?

If your car has been overheating, you may be wondering if there is a way to manually turn on the radiator fan. The answer is yes, in most cases you can manually turn on the radiator fan. However, it is important to note that this should only be done as a last resort and when absolutely necessary.

If your car is overheating and the radiator fan is not coming on, this could be a sign of a more serious problem and you should take it to a mechanic as soon as possible.

How Do You Run a Radiator Fan Directly to a Battery?

If you want to run a radiator fan directly to a battery, there are a few things you need to keep in mind. First, make sure the fan is rated for the voltage of your battery. Second, connect the positive terminal of the battery to the positive lead of the fan, and connect the negative terminal of the battery to the negative lead of the fan.

Finally, turn on the switch or power button on the fan.

Frequently Asked Question About to Bypass Cooling Fan Relay

What Happens When a Fan Relay Fails?

When a fan relay fails, it can cause the engine to overheat. The engine will not be able to cool itself properly and this can lead to damage to the engine components. If the engine overheats, it can also cause the oil to break down and burn up, which can clog the filter and cause an oil pressure drop.

How Do You Know If a Fan Relay is Stuck?

If you have a stuck fan relay, there are a few things you can do to try and fix it. First, check the fuse box to see if the fuse for the fan relay is blown. If it is, replace it with a new one and see if that fixes the problem.

If not, then you’ll need to check the wiring going to the relay to make sure there’s no corrosion or damage. If everything looks good there, then you may need to replace the relay itself.

How To Bypass Fan Relay in 1 Minute !!


Assuming you would like a summary of the blog post titled “How to Bypass Cooling Fan Relay”: The blog post explains how to bypass a cooling fan relay by using a single wire. The author provides step-by-step instructions on how to do this, including which type of wire to use and where to connect it.

They also provide a diagram to help readers visualize the process.