Understanding a 12volt relay wiring diagram is a fundamental skill for anyone working with automotive electrical systems, home projects, or even some basic electronics. A 12volt relay wiring diagram shows you exactly how to connect a relay, a small but powerful electrical switch, to control higher-current devices using a lower-current signal. This guide will demystify these diagrams, making them easy to understand and apply.
What is a 12volt Relay Wiring Diagram and How is it Used?
At its core, a 12volt relay wiring diagram is a blueprint for using a relay to control a circuit. Think of a relay as an electrically operated switch. It has two main parts: a coil and contacts. When a small amount of electricity (the control signal) is applied to the coil, it creates a magnetic field. This magnetic field then physically moves the contacts, allowing or interrupting the flow of a larger amount of electricity in a separate circuit. This is incredibly useful because it means you can use a low-power switch, like a button on your dashboard, to control a high-power device, such as a powerful horn or a set of fog lights, without overloading the switch itself.
The key benefit of using a relay, and therefore understanding its wiring diagram, is protection and efficiency. Here's why they are so important:
- Protecting Switches: Low-current switches are not designed to handle the high amperage required by many accessories. Relays act as an intermediary, taking the load off the switch.
- Controlling High-Power Devices: You can turn on devices that draw a lot of power, like powerful fans, pumps, or even starter motors, with a simple, low-power signal.
- Simplifying Wiring: In complex systems, relays can help manage multiple circuits from a single control point.
Let's look at a typical 4-pin relay and its connections as shown in a 12volt relay wiring diagram. The four pins are usually:
| Pin Number (Common) | Function |
|---|---|
| 30 | Common terminal, directly connected to the power source for the switched device. |
| 87 | Normally Open (NO) terminal. This is where power is sent when the relay is activated. |
| 85 | Coil Ground. Connects to the negative terminal of the power source to complete the coil circuit. |
| 86 | Coil Positive. Connects to the control switch, which then connects to the positive terminal of the power source. |
The diagram will show how to connect your 12-volt power source, your control switch, and the device you want to power to these specific terminals. For example, to turn on a light: you'd connect battery positive to pin 30, the light's positive wire to pin 87, the control switch to pin 86, and the control switch's other side to ground (pin 85). When the switch is flipped, current flows through pins 86 and 85, activating the relay and connecting power from pin 30 to pin 87, thus turning on the light.
To see a visual representation and truly grasp how these connections come together, we highly recommend referring to the detailed diagrams available in the resources provided in the next section.