How to Test a Relay With a Battery (With Pics): The Easy Way

 How To Test A Relay With A Battery

A car relay is a device that is used to control the flow of electricity in a vehicle. It uses an electromagnet to open or close a switch. It is typically used to control the headlights, taillights, fans, motors, and other electrical components. The relay is activated by a switch that is operated by the driver. When the switch is turned on, the relay closes the circuit and allows current to flow to the lights.

Testing a relay with a battery is a simple process that can be done with a battery. In this article, we will show you how to test a relay with a battery (with pictures).

How To Test A Relay With A Battery


A relay has two circuits, the primary circuit is also known as a coil circuit containing terminals 85 and 86. Similarly, the secondary circuit is called high amperage or load circuit containing terminals 30 and 87. In the coil circuit terminal, 85 is most often connected to a negative power, and terminal 86 is connected to a positive power source.

In the secondary circuit, a terminal that goes to the relay is referred to as 30. It is also known as the Power In Terminal, and the second terminal is 87, known as the Load Terminal or Power Out Terminal. When the relay is activated, power is supplied through terminal 30 and exits through terminal 87.

To test a car relay with a battery, you will need a battery, a four-pin relay, and an alligator clip. Following is the procedure to test a car relay with a battery.

How To Test A 4-Pin Relay With A 12V Battery
How To Test A 4-Pin Relay With A 12V Battery
  • To test a relay, you need a 12-volt battery. This is because the relay needs a certain amount of voltage to operate correctly.
  • Take a 4-pin relay, which consisted of the coil and high amperage circuit.
  • Connect the alligator clip with terminal 85 of the relay and another end with the battery negative terminal.
  • Similarly, connect one end of the second alligator clip with terminal 86 and the other end with the battery-positive terminal. You will hear a clicking sound. This is an indication that the coil circuit is fine.
  •  Also, add a load to test the high amperage circuit to see if it is working.
  • First, you should connect terminal 30 of the high amperage circuit to the battery-positive power source.
  • You should add a small load (bulb) to terminal 87 of the relay. Connect one end of the bulb to the relay’s terminal 87 and the other end with a battery-negative power source or ground somewhere to the car frame.
  • Now, energize the relay, you will hear a clicking sound simultaneously the bulb will lighten up. It indicates the relay is working.
  • If the relay makes no clicking sound, it indicates that the relay’s coil circuit is not functioning. If the relay is making clicking noises but the bulb does not illuminate, it signifies that the high amperage circuit has malfunctioned. In both cases, the relay is to blame.

Related Post: How To Wire A 4 Pin Relay For Horn & Lights With Diagram

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