Upgrading your vehicle’s sound system with an after-market air horn requires the installation of a relay to enhance performance and protect the electrical system. This intricate process involves precise wiring techniques to ensure seamless integration and optimal functionality. By following a step-by-step guide, you can successfully navigate the wiring process and unleash the full potential of your air horn.
Before embarking on the wiring task, gather essential tools such as wire strippers, electrical tape, and a multimeter. Identifying the relay’s terminals is crucial, as they determine the proper wire connections. Typically, the relay will have terminals labeled as “85,” “86,” “87,” and “30.” Understanding these designations is paramount for a successful wiring configuration.
The main power source for the relay is typically obtained from the vehicle’s battery or a dedicated power distribution block. Connect a wire from the positive terminal of the power source to terminal “30” on the relay. Likewise, connect a wire from terminal “87” on the relay to the positive terminal of the air horn. To activate the relay, a switching signal is required. This signal is usually provided by the vehicle’s horn button. Connect a wire from terminal “85” on the relay to the positive terminal of the horn button. Finally, connect a wire from terminal “86” on the relay to a suitable ground point on the vehicle’s chassis.
Introduction to Wiring an Aftermarket Air Horn Relay
Installing an aftermarket air horn requires a relay to ensure the proper flow of electricity and prevent damage to your vehicle’s electrical system. Wiring an air horn relay is a relatively straightforward process that can be completed with basic tools and some electrical knowledge. In this guide, we will provide a comprehensive explanation of the wiring process, including detailed instructions and troubleshooting tips.
Understanding the Relay
A relay is an electromagnetic switch that uses a small current to control a larger current. In the case of an air horn, the relay serves as a gatekeeper, allowing the high current from the battery to flow to the air horn when the horn button is pressed. The relay has four terminals: one for the low-current signal from the horn button, one for the high-current supply from the battery, one for the high-current output to the air horn, and one for the ground connection.
Terminal Functions
| Terminal | Function |
|---|---|
| 30 | Battery (high current) |
| 86 | Horn button (low current) |
| 87 | Air horn (high current) |
| 85 | Ground |
Identifying Necessary Components and Tools
Essential Components
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Aftermarket air horn
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Relay (typically a 12-volt, 4-pin or 5-pin relay)
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Wiring harness (usually included with the air horn or relay)
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Fuse (appropriate amperage for the air horn)
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Female spade terminals (for connecting to the relay)
Essential Tools
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Electrical tape
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Wire strippers
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Crimping tool
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Multimeter (optional but recommended for testing)
Detailed Guide to Wiring a Relay
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Locate the terminals on the relay:
- Pin 30: Power input from the battery
- Pin 85: Control input from the switch
- Pin 86: Ground (usually connected to the chassis of the vehicle)
- Pin 87: Output to the air horn
- Pin 87a (optional): Not usually used
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Connect the wires to the relay:
a. Strip the ends of the wires about 1/4" to 1/2". b. Crimp female spade terminals onto the stripped wires. c. Insert the wires into the appropriate terminals on the relay. d. Tighten the terminal screws to secure the wires. -
Connect the relay to the battery:
- Connect the wire from Pin 30 to the positive terminal of the battery.
- Install an inline fuse in the wire to protect against electrical damage.
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Connect the relay to the ground:
- Connect the wire from Pin 86 to a ground point on the vehicle’s chassis.
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Connect the relay to the air horn:
- Connect the wire from Pin 87 to the positive terminal of the air horn.
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Connect the relay to the switch:
- Connect the wire from Pin 85 to the switch that will activate the air horn.
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Test the air horn:
- Turn on the switch and press the air horn button.
- The air horn should sound when the switch is activated.
- If the air horn does not sound, use a multimeter to troubleshoot the circuit and identify any open or short circuits.
Selecting the Appropriate Relay
Choosing the correct relay is crucial for the proper functioning of your air horn relay system. Consider the following factors:
- Current capacity: The relay should be able to handle the current draw of your air horn. Consult the manufacturer’s specifications to determine the required current capacity.
- Number of contacts: Select a relay with the appropriate number of contacts based on your air horn’s wiring configuration. Typically, an air horn relay system requires a relay with at least four contacts (two for the air horn and two for the switch).
- Coil voltage: The relay’s coil voltage should match the voltage of your vehicle’s electrical system. Most vehicles use 12-volt electrical systems, so choose a relay with a 12-volt coil.
- Physical size: Ensure the relay you select is of a suitable size to fit in the designated location in your vehicle. Consider the dimensions of the relay and the available mounting space.
The table below summarizes the key aspects to consider when selecting an air horn relay:
| Parameter | Consideration |
|---|---|
| Current capacity | Match the relay’s capacity to the air horn’s current draw |
| Number of contacts | Typically requires a relay with four contacts (two for air horn, two for switch) |
| Coil voltage | Match the relay’s coil voltage to the vehicle’s electrical system (e.g., 12-volt for most vehicles) |
| Physical size | Choose a relay that fits in the available mounting space |
Wiring the Relay to the Air Horn
Connect the relay’s output terminals to the air horn’s power wires. Typically, the output terminals will be labeled with “+12V” or “Power” and “Ground.” Match the air horn’s power wires to the corresponding relay terminals, ensuring that the positive wire is connected to the “+12V” or “Power” terminal and the negative wire is connected to the “Ground” terminal.
Securely tighten the connections using electrical tape or wire nuts to prevent any loose connections that may cause electrical issues or damage.
Testing the Air Horn Relay
With the relay installed and wired, test its functionality by pressing the air horn button. The air horn should sound immediately, indicating that the relay is working correctly. If the air horn does not sound, check the relay connections, fuse, and power supply to ensure they are properly connected and functioning.
Connecting the Relay to the Power Source
Once you have identified the relay’s terminals, connect the power wires to the appropriate ones. Typically, the relay will have three terminals: a positive terminal, a negative terminal, and a switched terminal. The positive terminal will be connected to the positive terminal of the battery or another power source. The negative terminal will be connected to the negative terminal of the battery or the chassis of the vehicle. The switched terminal will be connected to the horn.
Selecting the Right Wire Gauge
When selecting the wire gauge for the power wires, it is important to consider the current draw of the horn. Air horns can draw a significant amount of current, so it is important to use a wire gauge that is thick enough to handle the load. Refer to the table below for recommended wire gauges based on the current draw of the horn.
| Current Draw (Amps) | Wire Gauge |
|---|---|
| 10-20 | 12 AWG |
| 20-30 | 10 AWG |
| 30-40 | 8 AWG |
Connecting the Wires
To connect the wires to the relay terminals, use crimp connectors or solder and heat shrink tubing. Crimp connectors are easier to use, but solder and heat shrink tubing provide a more permanent and secure connection. Once the wires are connected, insulate the terminals with electrical tape or heat shrink tubing.
Choosing a Suitable Mounting Location
Selecting the ideal mounting location for your aftermarket air horn relay is crucial to ensure its longevity and optimal performance. Consider the following factors when making this decision:
Accessibility
Choose a location that allows for easy access to the relay in the event of maintenance or troubleshooting. Avoid areas that are difficult to reach or obstructed by other components.
Environmental Protection
The mounting location should provide adequate protection from the elements, such as moisture, heat, and vibration. Avoid installing the relay in areas exposed to direct sunlight or extreme temperatures.
Compatibility with Other Components
Ensure that the chosen location doesn’t interfere with other electrical components or wiring harnesses. Maintain a safe distance from sensitive elements and avoid areas with high electrical noise.
Secure Mounting
The mounting location should ensure a secure and vibration-free installation. Choose a flat surface with sufficient support to prevent the relay from loosening or moving over time.
Room for Wiring
Consider the space required for wiring connections. Ensure that there is enough room for the relay terminals and associated wiring without any overcrowding or strain.
Avoidance of Heat Sources
Relays generate heat during operation. Avoid mounting the relay near heat-producing components such as engines or exhaust systems. This will help prevent overheating and extend the lifespan of the relay.
| Suitable Locations | Unsuitable Locations |
|---|---|
| Behind Grille | Inside Engine Bay |
| Fender Well | Directly on Engine Block |
| Firewall | Near Exhaust System |
Testing the Relay Installation
- Connect the positive (+) terminal of a 12-volt battery to the relay’s terminal 30 (power input).
- Connect the negative (-) terminal of the battery to the relay’s terminal 85 (ground).
- Connect a multimeter to the relay’s terminal 87 (power output).
- The multimeter should read 12 volts when a jumper wire is connected from the relay’s terminal 86 (control input) to the positive (+) terminal of the battery.
- The multimeter should read 0 volts when the jumper wire is disconnected.
Checking the Relay’s Operation
- Install the relay in the vehicle.
- Connect the positive (+) wire from the horn to the relay’s terminal 87 (power output).
- Connect the negative (-) wire from the horn to the vehicle’s ground.
- Connect the positive (+) wire from the battery to the relay’s terminal 30 (power input).
- Connect the negative (-) wire from the battery to the relay’s terminal 85 (ground).
- Press the horn button. The horn should sound if the relay is working properly.
- Troubleshooting
If the horn does not sound when the horn button is pressed, check the following:
- The relay is properly installed.
- The fuses are not blown.
- The horn is not defective.
If all of these are checked and the horn still does not sound, the relay may be defective and should be replaced.
Troubleshooting Common Wiring Issues
8. Relay Not Clicking
Here are several possible causes and solutions for a relay that is not clicking:
| Possible Cause | Solution |
|---|---|
| No power to the relay coil | Check for power at the relay terminals and ensure that the wiring is correct. |
| Open circuit in the relay coil | Use a multimeter to test for continuity in the relay coil. If the coil is open, replace the relay. |
| Shorted ground connection | Check the ground connection for the relay and ensure that it is making a secure connection. |
| Damaged relay | If the relay has been damaged, it will need to be replaced. |
| Incorrect wiring | Ensure that the relay is wired correctly according to the instructions provided. Refer to the wiring diagram for proper connections. |
| Coil resistance too high | Check the resistance of the relay coil and compare it to the specifications provided. If the resistance is too high, replace the relay. |
| Faulty switch | If the switch controlling the relay is faulty, it will not be able to send a signal to the relay coil. Test the switch and replace it if necessary. |
| Blown fuse | Check the fuse that supplies power to the relay coil. If the fuse is blown, replace it with one of the same amperage. |
Safety Precautions for Wiring
To ensure a safe and successful wiring installation, follow these precautions:
1. Disconnect the Battery
Start by disconnecting the negative terminal of the battery. This will prevent any electrical shocks or damage to the vehicle’s electrical system.
2. Wear Protective Gloves
Wear insulated gloves to protect your hands from sharp edges and electrical components.
3. Use Appropriate Wiring
Select wiring with the correct gauge and insulation for the horn’s current draw. Avoid using undersized or damaged wires.
4. Secure Connections
All wire connections should be securely fastened using crimp connectors or solder. Loose connections can lead to voltage drop or electrical fires.
5. Route Wires Safely
Avoid routing wires over sharp edges or near moving parts. Secure wires with zip ties or wire looms to prevent damage.
6. Use a Fuse
Install a fuse in the power wire to protect the relay and horn from electrical overloads.
7. Check for Shorts
Before connecting the battery, use a multimeter to check for any shorts between the wires. This can prevent potential damage.
8. Reconnect the Battery
Once the wiring is complete, reconnect the negative terminal of the battery.
9. Test the Horn
Activate the horn to ensure it is functioning properly. Listen for any rattling or buzzing sounds, which may indicate an issue with the wiring or horn.
| Wire Size | Current Draw |
|---|---|
| 16 AWG | Up to 10 Amps |
| 14 AWG | Up to 15 Amps |
| 12 AWG | Up to 20 Amps |
How to Wire an Aftermarket Air Horn Relay
Materials You’ll Need:
- Air horn
- Wiring harness
- Relay
- Wire strippers/crimpers
- Electrical tape
- Fuses (optional)
Step-by-Step Instructions:
- Disconnect the vehicle’s battery before beginning any wiring.
- Choose a suitable mounting location for the relay near the horn.
- Connect the positive (+) terminal of the battery to the “IN” terminal of the relay.
- Connect the positive (+) terminal of the horn to the “OUT” terminal of the relay.
- Connect the ground (-) terminal of the horn to a suitable ground point on the vehicle’s chassis.
- Connect the “ON” terminal of the relay to a switched 12V source (e.g., ignition switch).
- Connect the “GND” terminal of the relay to a ground point on the vehicle’s chassis.
- Connect the negative (-) terminal of the battery to one end of the rocker switch.
- Connect the other end of the rocker switch to the “ON” terminal of the relay.
- Secure all connections with zip ties or other strain relief measures.
- Wrap all wire connections with electrical tape for insulation and protection.
- Check the wiring for any loose or damaged connections.
- Reconnect the vehicle’s battery.
- Test the air horn to ensure it functions properly.
Conclusion: Ensuring Proper Functioning of the Air Horn
- Ensure that all connections are made securely and with proper polarity (+/-).
- Inspect the air horn for any damage or leaks.
- Test the air horn regularly to ensure it is functioning as intended.
- If any issues arise, troubleshoot the wiring or horn and make necessary repairs.
- Consider installing a fuse in the power line to protect the relay and other electrical components in case of a short circuit.
How to Wire an Aftermarket Air Horn Relay
Installing an aftermarket air horn can enhance the safety and visibility of your vehicle. A relay is an essential component of this installation, acting as an intermediary switch that controls the flow of power from the battery to the air horn. Here’s a step-by-step guide on how to wire an aftermarket air horn relay.
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Gather your materials:
- Aftermarket air horn
- Relay
- Wire connectors
- Electrical tape
- Crimping tool
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Locate a suitable mounting point for the relay, typically near the battery. Use screws or bolts to secure the relay in place.
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Connect the positive terminal of the battery to the relay’s “30” terminal using a wire connector and crimp it securely. This will provide power to the relay.
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Connect the air horn’s positive wire to the relay’s “87” terminal. This will send power to the air horn when the relay is activated.
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Ground the relay by connecting the relay’s “85” terminal to a metal surface on the vehicle’s frame using a wire connector and crimp it. This will complete the circuit and allow the relay to operate.
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Connect the switch that will activate the air horn to the relay’s “86” terminal. When the switch is closed, it will trigger the relay to activate, sending power to the air horn.
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Insulate all connections using electrical tape to prevent short circuits.
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Test the air horn to ensure it’s working correctly.
People Also Ask
What is the purpose of an air horn relay?
An air horn relay acts as a switch that controls the flow of power from the battery to the air horn, allowing you to activate the horn without drawing excessive current from the vehicle’s electrical system.
What type of relay should I use for an aftermarket air horn?
Use a relay that can handle the amperage of the air horn you’re installing. Consult the air horn manufacturer’s instructions for the recommended relay specifications.
Where should I mount the air horn relay?
Mount the relay in a dry, well-ventilated area near the battery, where it can easily access the necessary connections.
Can I use a relay to wire multiple air horns?
Yes, you can use a relay to wire multiple air horns. However, ensure that the relay can handle the combined amperage of all the air horns.