Are you ready to turn heads (and a few ears) with a robust aftermarket air horn? Upgrading to a louder and more powerful air horn is the perfect way to make your presence known on the road. Whether it’s for safety, practicality, or just for fun, installing an aftermarket air horn is a rewarding DIY project. However, to unlock the full potential of your new horn and ensure your vehicle’s electrical system remains safe, wiring a relay is a must.
This comprehensive guide will walk you through the process of wiring an aftermarket air horn relay step by step—even if you’re a beginner. By the end, you’ll not only have a louder horn but also a properly installed system that’s reliable and safe.
What Is an Air Horn Relay?
Before we jump into the installation process, let’s cover the fundamentals. An air horn relay is an electrical component that acts as a switch to control the high current required by your air horn.
Why is a relay important? Using a relay ensures that your vehicle’s factory wiring doesn’t handle more power than it was designed for. Without a relay, the wiring could overheat, the fuse could blow constantly, or worse—you could damage your car’s electrical system.
Benefits of Using a Relay for Air Horns
- Enhanced Performance: Relays allow sufficient power to flow to your horn, ensuring it reaches its maximum volume.
- Prevents Circuit Overload: Keeps your vehicle’s existing electrical system protected by avoiding excessive current draw.
- Durability: Relays reduce wear and tear on your horn switch and wiring, extending the lifespan of your air horn system.
Tools and Materials Needed for Wiring an Air Horn Relay
Before you start, gather all the tools and materials you’ll need to make the process smooth and hassle-free:
Essential Tools
- Wire cutters and strippers
- Multimeter or electrical tester
- Screwdriver set
- Socket wrench/ratchet (for mounting)
Materials
- Aftermarket air horn kit (including the air horn, mounting brackets, and air compressor, if applicable)
- 12V relay (with at least four terminals)
- Wiring harness or automotive-grade wires
- Inline fuse holder and fuse
- Electrical tape or heat-shrink tubing for insulation
- Zip ties for securing wires
Safety Gear
- Insulated gloves
- Safety goggles
Optional but helpful tools include a crimping tool for connectors and a wiring diagram for your specific vehicle.
How to Wire an Aftermarket Air Horn Relay
Follow these steps carefully, and you’ll have your air horn installed and ready to roar in no time.
Step 1: Prepare for Installation
- Park your vehicle on a flat, stable surface and turn off the ignition.
- Disconnect the vehicle’s battery to avoid accidental shorts or shocks. Always remove the negative battery cable first.
- Gather and inspect all components from your aftermarket air horn kit to ensure nothing is missing.
Step 2: Install the Air Horn on Your Vehicle
- Choose a suitable location for your air horn. Look for an area free of moving engine parts and away from excessive heat sources.
- Use the provided mounting brackets to secure the air horn. Ensure the horn is facing outward and slightly downward to prevent water damage.
- If your horn includes an air compressor, connect the provided air hose between the compressor and the horn.
Step 3: Position the Relay
- Identify a mounting location near the battery and air horn for the relay. This keeps wiring efficient and minimizes voltage drops.
- Secure the relay using zip ties, screws, or a relay mounting bracket to keep it from moving during operation.
Step 4: Connect the Wires
Now comes the wiring! Follow these connections carefully:
- Terminal 30: Connect this terminal to the positive terminal of your vehicle’s battery using a wire with an inline fuse. The fuse will protect the horn and relay from power surges.
- Terminal 85: Connect this to your vehicle’s factory horn switch or trigger wire. When you press the horn button, this wire activates the relay.
- Terminal 86: Ground this wire to a clean, unpainted metal surface on the vehicle chassis. Use a ring terminal for a secure ground connection.
- Terminal 87: Connect this to the positive terminal of the air horn. This will supply power to the horn when the relay is activated.
Step 5: Secure Ground Connections
Grounding is crucial for the system to function properly. Scrape off any paint or rust from your chosen grounding point to ensure a solid connection. Use a multimeter to test continuity before moving on.
Step 6: Double-Check Your Wiring
- Inspect all your connections to ensure accuracy.
- Use a multimeter to check for continuity on grounded and powered wires.
- Wrap exposed connections with electrical tape or heat-shrink tubing to prevent short circuits.
Step 7: Test the Air Horn
- Reconnect the battery’s negative terminal and turn on the ignition.
- Press the horn button to test your new air horn relay system.
- If the horn doesn’t work, check for loose connections, incorrect wiring, or a blown fuse and troubleshoot as needed.
Step 8: Clean Up and Finalize Installation
- Secure all wires along their routing paths using zip ties, keeping them away from high-heat areas and moving parts.
- If you removed any panels or covers during the process, reinstall them.
- Test the horn one final time to ensure everything is in working order.
Benefits of Properly Wiring an Air Horn Relay
Wiring your air horn relay correctly provides a range of advantages:
- Louder, Clearer Sound: Your horn operates at optimal performance.
- Electrical System Safety: No risk of overheating or damage to your factory wiring.
- Longer Equipment Lifespan: Protects your horn and relay from unnecessary wear and tear.
Common Mistakes to Avoid
- Skipping the inline fuse: Always use a fuse to prevent electrical damage.
- Using undersized wires: Thin wires can overheat and fail under high current loads.
- Poor grounding: Improper grounding leads to inconsistent horn performance.
Maintenance Tips for Your Aftermarket Air Horn
- Check wiring and connections regularly for signs of corrosion or wear.
- Clean the horn and compressor to remove dust and debris.
- Test the horn periodically to ensure it’s functioning properly.
FAQs about Wiring an Aftermarket Air Horn Relay
1. Do I need a professional to install an air horn relay?
Not necessarily! This step-by-step guide is designed to make the installation DIY-friendly.
2. Can I wire an air horn without a relay?
It’s not recommended. Without a relay, the higher current demand can damage your car’s electrical system.
3. What size fuse should I use?
Choose a fuse size based on your air horn’s amperage rating—usually a 20-30 amp fuse suffices.
4. How can I tell if my relay is faulty?
Common signs include a non-functioning horn, buzzing sounds, or frequently blown fuses.
5. Is it legal to use air horns on public roads?
Laws vary by region. Check your local regulations before using your air horn.
Enjoy the Power of Your New Air Horn
By following this guide, your aftermarket air horn is now wired for maximum performance and reliability. Safe travels, and don’t forget to turn heads (responsibly) with your new setup. Got questions about installation? Drop a comment below, and we’ll be happy to help!
