| Key Points |
|---|
| A relay is an electrical switch that allows a low-current signal to control a high-current load. |
| There are two types of relays commonly used in automotive applications: 4-pin and 5-pin relays. |
| The wiring diagram for a 4-pin relay typically includes a power supply, a ground connection, a control circuit, and a switched output. |
| The wiring diagram for a 5-pin relay typically includes all of the same components as a 4-pin relay, plus an additional power source for the control circuit. |
| When wiring a relay, it’s important to use proper gauge wire and ensure correct polarity to avoid damage to the relay or other components. |
| Relays can be used in a variety of automotive applications including lighting, horns, fans, and more. |
| Understanding how to wire 4-pin and 5-pin relays can be useful for DIY automotive projects and repairs. |
Understanding how to wire 4-pin and 5-pin relays is a handy skill for anyone involved in auto repairs or interested in electronics. These relays are among the most common types you’ll encounter, especially when dealing with automotive applications. They enable safer and more efficient management of high-current devices like headlights, fuel pumps, and cooling fans.
This guide will walk you through the process of wiring these relays, helping you understand their operation along the way.
What is a Relay?
Before we dive into the wiring, it’s helpful to understand what a relay is. Essentially, a relay is an electrically operated switch. It allows a low-power electrical circuit to control a separate, higher current circuit. This separation ensures the control circuit is protected from potential damage or safety risks posed by the high-power load.
4-Pin Relay
A standard 4-pin relay has four connections: two for the control circuit (85, 86) and two for the high-power circuit (30, 87).
Here’s a simple way to wire a 4-pin relay:
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Pin 30 - Connect this pin to the power source. This is the power that will be used by the relay to switch the device on.
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Pin 87 - This pin is connected to the device you want to power on.
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Pin 85 - Connect this pin to the ground or negative terminal on your power source.
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Pin 86 - This pin is connected to the switch that will activate the relay.
When power is applied to Pin 86 and ground to Pin 85, this activates the relay, connecting Pins 30 and 87, thus powering on the device.
5-Pin Relay
A 5-pin relay works similarly to a 4-pin relay, but it has an additional pin (87a) for an alternate power source or accessory. This pin can be used for an alternate function, such as keeping a light on when the relay’s primary function is off.
Here’s a simple way to wire a 5-pin relay:
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Pin 30 - Connect this pin to the power source.
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Pin 87 - Connect this pin to the device you want to power on.
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Pin 87a - This pin can be connected to a secondary device or accessory that you want to power when the primary device is off.
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Pin 85 - Connect this pin to the ground or negative terminal on your power source.
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Pin 86 - Connect this pin to the switch that will activate the relay.
With a 5-pin relay, when power is applied to Pin 86 and ground to Pin 85, the relay activates, connecting Pins 30 and 87, thus powering on the primary device. Pin 87a is disconnected in the activated state but can provide power in the relay’s de-energized state.
Final Thoughts
Both 4-pin and 5-pin relays offer a safe and efficient way to manage electrical devices that require high current. The additional pin on the 5-pin relay provides greater flexibility in controlling multiple devices.
Remember, when dealing with any electrical work, safety should always come first. Ensure your power source is disconnected before beginning work, and always double-check your wiring before applying power.
Understanding relay wiring can help you tackle a variety of electrical projects, from simple repairs to custom automotive upgrades. So the next time you need to manage a high-current device, consider reaching for a 4-pin or 5-pin relay and putting your newfound knowledge to use.
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What are 4-pin and 5-pin relays?
4-pin and 5-pin relays are types of electrical switches controlled by an electrical input signal. They’re commonly used in automotive and electronic applications. The main difference between them is that a 4-pin relay uses four wires for its operation, while a 5-pin relay uses five.
How do I wire a 4-pin relay?
To wire a 4-pin relay, first identify the pins which are usually labeled: 30 (power input), 85 (ground), 86 (trigger), and 87 (output). Connect the power input to the device you want to control and the ground to a clean metal surface. The trigger connects to the device that will switch the relay on, and the output connects to the power source.
How do I wire a 5-pin relay?
The wiring process for a 5-pin relay is similar to a 4-pin relay, but there is an extra pin (87a) which is the “Normally Closed” contact. This pin is connected to the output that you want to be on when the relay is not activated. When the relay is activated, the connection switches from pin 87a to pin 87 (the “Normally Open” contact), turning off the “Normally Closed” output and turning on the “Normally Open” output.
What is the function of the extra pin in a 5-pin relay?
The extra pin (87a) in a 5-pin relay acts as a “Normally Closed” contact. This means that when the relay is not powered, the electrical circuit is completed through this pin. When the relay is powered and triggered, the circuit switches over to the “Normally Open” pin (87), disconnecting the “Normally Closed” pin.
Are the diagrams for wiring 4-pin and 5-pin relays different?
Yes, the diagrams for wiring 4-pin and 5-pin relays are different mainly due to the presence of the extra “Normally Closed” pin in the 5-pin relay. However, they share the common principles of relay wiring where the power input, ground, trigger, and output are properly connected.
