How To Wire A Horn Relay?

A horn is one of the safety features of every vehicle; it helps to release the sound that creates an awareness or draws attention as you drive so that you do not get involved in an accident with a pedestrian or another vehicle on the road.

Since the horn is vital, ensuring that you fix a faulty horn is important. Therefore, understanding how to wire a horn relay will help you handle the situation of fixing a new horn component in your car.

The horn relay, circuit, and other components must be connected correctly in wiring a horn relay. The process of performing the horn relay wiring has been unveiled in this article for your consumption.

How To Wire A Horn Relay Step-by-step

3 pin horn relay wiring diagram

Wiring a car’s horn relay requires understanding the components needed for the horn relay wiring harness and the step-by-step process required to carry out the connection accurately. The following steps will guide you through the process of wiring a horn relay when you need to do so in your car.

Step 1: Locate and disconnect the original horn wire

Locate the original horn and disconnect the wire. Then, insert the car key into the ignition hole and turn it to the “ON” position. Then, press the horn button and check out for 12 volts-power in the wire by using a multimeter or a test light.

If you can’t get 12 volts when you press the horn and check with the multimeter, you can use a continuity checker and check for continuity between the negative terminal of the battery and the wire.

Step 2: Connect the wire to the relay

After disconnecting and checking the horn wire, if you find 12 volts, go ahead and connect the wire at terminal 85 to the relay. Then, connect terminal 86 to a metal spot in the vehicle by using a short 16 gauge wire with solderless connectors.

Step 3: Connect the horn wire

Now, connect the wire of the horn to terminal 86; then, connect terminal 85 to terminal 30. It would be best to wire the relay differently if you must find continuity between the wire of the horn and the car’s ground.

Step 4: Mount the horn and the relay

After connecting the wire to the terminals, go on and mount the vehicle’s new horn and the relay in a suitable spot under your car’s hood. You could choose a place near your car’s battery so that you don’t have to spend money unnecessarily in buying heavy gauge wire.

Step 5: Connect the solderless ring terminal.

Finally, connect one inline fuse holder’s wire to a solderless ring terminal, and connect it to the vehicle’s battery positive terminal. After that, use a ten gauge wire and a solderless butt connector to extend the fuse holder’s other side and connect it to terminal 30. The connection is better done with a female spade connector.

Thereafter, you could use a length of a piece of ten gauge wire and suitable solderless connectors to connect the horn to terminal 87 on the relay. In case there are two connectors in this area, go ahead and connect the other connector to a metal spot in your vehicle, using solderless connectors and ten gauge wire. You could check out for single horn wiring diagram or a dual horn relay wiring diagram to guide you properly.


Q: Does a horn need a relay?

Of course, a horn needs a relay. The horn relay is responsible for controlling the power supply to the horn circuit of your vehicle. Without it, the horn may not function because there will be no power supply.

The horn relay helps to switch a large current to your car’s horn from the button of the low-current horn in your car’s steering wheel. The horn circuit has a wire connected that closes the circuit when the switch grounds the wire, releasing the horn’s sound.

If your car has a faulty horn relay, the horn will lack the power to release its sound. In that case, you will need to consult a professional auto technician to fix the problem.

Q: Can I wire a horn without a relay?

Wiring a horn without a relay will only seem abortive because the essence of wiring the horn to function may not be achieved. The relay is a vital component in the horn circuit, and you will need a relay when wiring a horn.

The relay helps to control the power of the horn circuit. It helps to release the connection that completes the horn circuit and enables it to complete the circuit so that it can ring when you engage it.

Q: What happens if you don’t use a relay?

A relay plays a vital role in the proper functioning of the horn in your car. The connected wire closes the circuit when the switch is engaged so that the sound can be released.

If you wire the horn without using a relay, it will cause all the stress from the entire system to be transferred to the switch. When this happens, the switch is likely to fail or become defective as soon as possible.

Therefore, it would be best to use a relay so that the wiring is perfect enough to sustain the horn and its components over a reasonable period.

Q: Do you need to fuse a relay?

Yes, it would help if you fused a relay. When wiring a horn relay circuit, it would be best to be in this form; fuse/relay/load. Ideally, a fuse is usually the first item when connecting a circuit. When connecting or wiring, fuse the power cable based on the cable’s size and endeavor to protect the relay’s wire with a fuse.

The relay and the fuse serve different purposes. The relay is an electromechanical switch; while, a fuse is a piece of wire that has a low resistance. When a high current flows through the horn components that would have burnt the entire connection, the filament is heated up and burns or melts, thereby protecting the other parts from burning.

Q: What is the use of a horn relay?

A vehicle’s horn relay is an electronic component in the entire components of a vehicle’s horn circuit. The horn relay serves as the controller of the power supply to the car’s horn, and it functions by completing the power circuit of the horn to enable it to release the sound when engaged.

The horn relay is a vital component in the proper functioning of your car’s horn. The horn may not function without the horn relay. If you have a defective horn relay, the horn may not engage properly.

Final Words

The wiring process of a car’s horn relay has been unveiled in this article. I’m sure you now understand how to wire a horn relay using all of the components required for the connections. If you have been a DIYer and have a horn relay wiring kit, you should be able to do the connection or wiring by following the step-by-step guide provided in this article.

However, if you are unsure of your DIY capability, you may have to consult an expert auto technician to perform the wiring in a workshop. The whole process will cost you a few dollars to get the components for the wiring, and the labor cost will not break your pocket.

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Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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