Relays are an essential component in any electrical circuit. It is the go-to device for switching high voltages with a low voltage signal. A 12V relay wiring diagram 4 pin is one of the most common diagrams used for relays. This article will explain the four pins and their functions, how to wire a 4 pin relay, and some frequently asked questions about 12V relay wiring diagrams.
The Four Pins and Their Functions
Before we dive into how to wire a 4 pin relay, let’s review the four pins and their functions. A 4 pin relay has four pins or terminals. These terminals are labeled 85, 86, 87, and 30.
Pin 85 is the ground terminal. It is usually connected to the vehicle’s chassis or a ground wire.
Pin 86 is the input voltage terminal or coil+. It is usually connected to a switch or ignition source that provides a low voltage signal to activate the relay.
Pin 87 is the output voltage terminal or NO (Normally Open) contact. When the relay is activated, it connects pin 30 to pin 87, allowing current to flow from pin 30 to pin 87.
Pin 30 is the power input terminal or common contact. It is usually connected to the positive battery terminal or a power source that supplies power to the device that is being controlled by the relay.
How to Wire a 4 Pin Relay
Now that we understand the four pins and their functions, let’s take a look at how to wire a 4 pin relay.
The wiring diagram below shows the correct wiring for a 4 pin relay.
| Pin | Function | Wire Color |
|---|---|---|
| 85 | Ground | Black |
| 86 | Input Voltage | Red |
| 87 | Output Voltage | Blue |
| 30 | Power Input | Yellow |
Connect the wires to the corresponding pins on the relay and the device you are controlling with the relay.
For example, let’s say you are using a 4 pin relay to control a set of fog lights. The power input wire (yellow) would be connected to the positive battery terminal or a power source that supplies power to the fog lights. The ground wire (black) would be connected to the vehicle’s chassis or a ground wire. The input voltage wire (red) would be connected to a switch or ignition source that provides a low voltage signal to activate the relay. The output voltage wire (blue) would be connected to the positive wire of the fog lights.
FAQ
1. Can a 4 pin relay be used to control multiple devices?
Yes, a 4 pin relay can be used to control multiple devices. However, the power input wire (pin 30) must be able to handle the combined current draw of all the devices.
2. Can a 4 pin relay be used to switch high voltages?
Yes, a 4 pin relay can be used to switch high voltages. However, the voltage and current rating of the relay must be able to handle the load.
3. Can a 4 pin relay be used to switch AC voltages?
Yes, a 4 pin relay can be used to switch AC voltages. However, the relay must be rated for AC voltage and AC current.
4. Can a 4 pin relay be used with a microcontroller?
Yes, a 4 pin relay can be used with a microcontroller. However, a transistor or MOSFET may be required to drive the input voltage (pin 86) of the relay.
5. Can a 4 pin relay be used to switch polarity?
Yes, a 4 pin relay can be used to switch polarity. Simply connect the output voltage wire (pin 87) to the negative wire of the device you are controlling.
Hopefully, this article has given you a better understanding of 12V relay wiring diagrams and how to wire a 4 pin relay. Remember to always follow proper wiring practices and consult an expert if you are unsure.
