How To Test your Accord Fan Relay

How To Test your Accord Fan Relay


When you are experiencing overheating issues with your Honda Accord, it can be from several different causes. From clogged radiators to water pump inefficiencies and more, overheating can be a real headache if you aren’t on top of things.

We’ll be showing you how to test the Honda fan relay in a 1999 Honda Accord 4 cylinder, but this How To Test your Accord Fan Relay guide also applies from years 1998-2001.

When your radiator fan motor relay goes bad or does not turn on your radiator fans correctly, your Accord will overheat may have other issues. Some common symptoms from overheating are ;

  • High temperature readings
  • Your car will not start when hot
  • Coolant is boiling in overflow tank
  • Heater does not work
  • Exhaust smells sweet

Don’t forget to check out our How to Diagnose overheating cars, by checking the link here. Before we begin our How to Test Your Accord Fan Relay, please take the utmost care when working around your radiator fans. They can turn on without warning and always work on your car when cold.

Open your hood and take some time to locate your fusebox, which is mounted in front of the passenger side of the firewall. Remove the top cover to expose your fusebox and relays, check your radiator fan relays and remove them. Inspect for any damage to the pins or the body of the relay, such as bubbling or melting.


Your radiator fan relay is located on the right hand side, the middle of the 3 relays in this section of your main engine bay fusebox.



We’ll be starting our How To Test your Accord Fan Relay tutorial by testing for power at pin 1 and pin 3 on your relay. Take some time to familiarize yourself with the Honda Accord radiator fan relay pinout, shown below.


Using your voltmeter test the socket for PIN 1 on your fusebox relay. This should be a 12 volt signal that is constant, regardless of key placement. If you do not find 12 volts here, check fuse 57 as shown below. Replace this 20 amp fuse if it’s blown, and there should be constant 12 volts of power at pin 1.


If you have power at the terminal for PIN 1 you can now put the key to the “ON” position and check for switched power at the terminal for PIN 3.

Remember that this pin is switched power and should read 12 volts with the key at the “ON” position. If you do not see switched 12 volts at this pin, open the interior dash panel open on the driver side and replace the 7.5 amp fan relay fuse.

If your fans still refuse to turn on and you have power at these two terminals our next test is to force your coolant temperature fan switch on.

Unplug the coolant temperature fan switch located on thermostat, this is a brown plug and it just two wires. Jumper these two wires together, and plug your Accord radiator relay back in place with the key to the “ON” position. If your fans turn on, you should replace your coolant temperature fan switch right away. The part number for this sensor is 37760-P00-003, and is the reason why your Honda Accord is overheating.



If your fan does not turn on even with this fan switch connector jumpered, it’s time to bypass the switch and send 12 volts to the fans directly to see if it’s your fans or your fan relays that’s the problem.


Using a paperclip or thin wire, jumper PIN 1 and PIN 2 on your fusebox, not your relay. Turn the key to the “ON” position and your fans should now turn on since we are bypassing the Honda Accord radiator fan relay all together.

If your fans still do not turn on, the problem is not your Honda Accord radiator fan relay but your automotive fans or the wiring. Check here for our How To Test your Radiator fans to eliminate the fans as being the problem. If the wiring checks out, your fans must be replaced.

If your fans do turn on, our Honda Accord radiator fan relay must be replaced. The part number for this unit is 37980-RAD-L11 and can also be found under the following part numbers :


That does it for our How To Test Your Accord Fan Relay writeup, please leave us any questions or comments below.