When it comes to increasing the brightness and efficiency of your vehicle’s headlights, using a relay is a simple and effective solution. In this article, we’ll discuss what a relay is, how it works, and provide wiring diagrams for two different types of 12 volt headlight relays.
What is a Relay?
A relay is an electrically operated switch that allows a low current signal to control a high current circuit. In the case of headlights, a relay can be used to allow a stronger power source to activate the lights, providing a brighter and more consistent beam.
The use of a relay also reduces the load on the headlight switch, leading to a longer lifespan for the switch and reducing the risk of overheating or failure.
Relays can be found in various applications and are designed for specific uses. Some relays are designed for switching high voltage while others are designed for switching high current with low voltage control circuits. In this article, we will focus on relays used for headlight circuits in vehicles.
Before we dive into the wiring diagrams, let’s take a closer look at how a relay works.
How Does a Relay Work?
A relay has four main components: the coil, the armature, the contact, and the spring. When current flows through the coil, it creates a magnetic field that pulls the armature towards it. This movement causes the contact to close, allowing current to flow through the high current circuit.
When the coil is de-energized, the spring returns the armature to its resting position and the contact disconnects, interrupting the high current circuit.
The use of a relay allows for the control of a high current circuit using a low current control circuit. This is useful in many applications, including vehicle headlights.
Wiring Diagrams
There are two main types of 12 volt headlight relays: single relay and dual relay.
Single Relay Wiring Diagram
The single relay wiring diagram is the simpler of the two and involves only one relay. This type of relay is best used for vehicles with two headlights that have a common ground. Here’s how to wire it:
| Wire Color | Function |
|---|---|
| Yellow | Headlight Power (from battery) |
| White | Headlight Connection (to headlight switch) |
| Black | Ground Connection (to vehicle chassis) |
| Blue | Control Circuit (to headlight switch) |
Here’s how to connect the wires:
- Connect the yellow wire to the positive terminal of the battery.
- Connect the white wire to the connection on the back of the headlight switch that controls the headlights.
- Connect the black wire to a clean, bare metal part of the vehicle chassis.
- Connect the blue wire to the other connection on the back of the headlight switch that controls the headlights.
- Connect the other end of the blue wire to the control circuit terminal on the relay.
- Connect the other end of the yellow wire to the power terminal on the relay.
- Connect the other end of the white wire to the normally open terminal on the relay.
- Connect the other end of the black wire to the ground terminal on the relay.
Dual Relay Wiring Diagram
The dual relay wiring diagram is more complex, but it provides greater control over the headlights. This type of relay is best used for vehicles with two headlights that do not share a common ground. Here’s how to wire it:
| Wire Color | Function |
|---|---|
| Yellow (Relay 1) | Headlight Power (from battery) |
| White (Relay 1) | Control Circuit (to headlight switch) |
| Yellow (Relay 2) | Headlight Power (from battery) |
| White (Relay 2) | Control Circuit (to headlight switch) |
| Black (Relay 1) | Ground Connection (to vehicle chassis) |
| Black (Relay 2) | Ground Connection (to vehicle chassis) |
Here’s how to connect the wires:
- Connect the yellow wire from relay 1 to the positive terminal of the battery.
- Connect the white wire from relay 1 to the connection on the back of the headlight switch that controls the right headlight.
- Connect the black wire from relay 1 to a clean, bare metal part of the vehicle chassis.
- Connect the yellow wire from relay 2 to the positive terminal of the battery.
- Connect the white wire from relay 2 to the connection on the back of the headlight switch that controls the left headlight.
- Connect the black wire from relay 2 to a clean, bare metal part of the vehicle chassis.
- Connect the control circuit terminal on relay 1 to the control circuit terminal on relay 2.
- Connect the power terminal on relay 1 to the normally closed terminal on relay 2.
- Connect the power terminal on relay 2 to the normally closed terminal on relay 1.
- Connect the ground terminal on relay 1 to the ground terminal on relay 2.
FAQ
Q: Can I use any relay for my headlights?
A: No, it is important to use a relay specifically designed for headlight circuits. Using the wrong type of relay can lead to a variety of issues, including overheating, failure, and damage to other components.
Q: Will using a relay increase the brightness of my headlights?
A: Yes, using a relay can increase the brightness of your headlights by allowing a stronger power source to activate the lights. This provides a more consistent and brighter beam and reduces the load on the headlight switch, leading to a longer lifespan for the switch.
Q: How difficult is it to install a relay for my headlights?
A: The installation of a relay for your headlights is a relatively simple process that can be completed in a few hours with basic tools and wiring knowledge. However, if you are not comfortable working with wiring, it is recommended that you seek the assistance of a professional mechanic or electrician.
Q: Can I install a relay for my high beams as well?
A: Yes, you can install a relay for your high beams using a similar wiring diagram. However, you will need to use a separate relay for the high beams and ensure that the wiring is connected correctly to avoid damaging the components.
Q: How long will a relay last?
A: The lifespan of a relay can vary depending on the quality of the component and the conditions of its use. However, a well-designed and maintained relay can last for many years and provide reliable performance throughout its lifespan.
Q: Can I use a relay for other components in my vehicle?
A: Yes, relays can be used for a variety of components in a vehicle, including fog lights, horns, and cooling fans. However, it is important to ensure that the relay is designed for the specific component and that the wiring is connected correctly to avoid damaging the components.
Now that you understand the benefits of using a relay for your headlights and have the wiring diagrams for two different types of 12 volt headlight relays, you can enhance the brightness and efficiency of your vehicle’s headlights with ease.
