5 pin relay
What Is a Relay?
A relay is an electromagnet switch, which uses a small amount of electricity to control a much larger amount of electricity. Think of it as a small child being in charge of a super strong professional wrestler. The child can ask the wrestler to move a couch, and it's no effort for the child, and no problem for the wrestler. Relays are also often used to control the flow of electricity in a different location from the controller itself. For example: The child lives in Massachusetts and calls his pro-wrestler uncle in Florida to requests that his uncle bench presses his own couch 5 times. Again, no effort for the child, and no problem for the pro-wrestler. A relay works the same way. A high amperage electric fuel pump can be turned on under the car while being controlled by a tiny low amperage switch mounted in a car's dashboard.
Why Do You Need a Relay?
In the automotive world, relays allow you to use a small switch inside the car, to remotely control the flow of electricity through a larger amperage circuit located any distance away from the switch. Most switches used in the automotive world are only rated to handle a small amount of amperage. Many circuits in a car are rated at amperages larger than the switches are rated for, which means if the circuit were to be wired through a switch directly, the switch would melt & break. However, if a relay is used, the circuit becomes much safer and more reliable. Most relays are rated much higher than switches. So you could use a 5 amp switch to remotely control the 30 amp relay. The 5 amp switch tells the relay to turn on and off. The 30 amp relay controls the high amperage circuit.
How to Wire a 5 Pin Relay?
Pin 30 - Power goes from the battery and into this pin, through a fuse. Pin 87 - Power comes out of this and goes to any accessory when your switch is turned ON. Pin 86 - Power goes into this from the switch. Pin 85 - This goes directly to ground. Pin 87A - Power comes out of this when the switch is OFF. It do not need to be used, and can be ignored entirely if it is not needed.