How To Wire An Automotive Relay

Summary

This video provides an in-depth explanation of automotive relays, detailing their function in managing electrical loads to prevent damage to switches and wiring. It covers the workings of both 4-terminal and 5-terminal relays, including wiring configurations and standards. The video also discusses specialized relays, such as time delay and diode-protected relays, emphasizing their applications in various automotive scenarios. Viewers will gain a practical understanding of how to wire relays correctly, ensuring safe and effective installation for accessories like cooling fans and lighting.

Takeaways

• 🔌 A relay is essential in automotive applications to prevent circuit damage from high amperage loads.
• ⚡ Relays allow low-power switches to control high-power devices, typically managing loads of 30 to 50 amps.
• 🔄 There are different types of relays, including 4-terminal (single throw) and 5-terminal (double throw) relays.
• 📏 The 5-terminal relay is commonly used for accessories with reversible motors, like power windows.
• ⚙️ Proper wiring is crucial; the DIN 72552 standard governs terminal connections for reliability and safety.
• 🔋 Terminal 30 connects to the battery feed, while terminal 87 connects to the load (accessory) being powered.
• 🛡️ Time delay relays are used to control circuits based on timed events, such as keeping headlights on after the ignition is off.
• ⚡ Diode and resistor-protected relays safeguard sensitive electronics from voltage spikes when the relay is turned off.
• 📊 When replacing a relay, ensure to use one with the same terminal layout and check the amperage requirements for proper wire gauge.
• 🔍 Micro relays, which are smaller versions, also follow the same principles but may have different terminal labeling.

Q & A

What is the primary function of a relay in automotive applications?

A relay is used to handle higher amperage loads that an inline switch or circuit cannot manage, preventing damage to switches or wiring.

How does a relay work when energized?

When energized, a relay's electromagnetic coil pulls contacts together, completing or breaking a circuit to activate the desired accessory.

What are the common types of relays used in the automotive industry?

The most common types are the 4-terminal relay, known as a single throw, and the 5-terminal relay, often referred to as a double throw.

What is the difference between a 4-terminal relay and a 5-terminal relay?

A 4-terminal relay typically has a normally open contact, while a 5-terminal relay can switch between two power sources, making it suitable for reversible motors.

What does the terminal number 87 represent in a relay setup?

Terminal number 87 is connected to the accessory being powered and is also known as the load.

What is the significance of following DIN 72552 standards in wiring relays?

Following DIN 72552 standards ensures proper terminal connections, which is crucial for the relay's correct functioning and safety.

What is a time delay relay, and where is it commonly used?

A time delay relay controls a circuit based on a predetermined time event and is often used to keep headlights on for a while after the ignition is turned off.

Why are diode or resistor protected relays important?

These relays protect sensitive electronics from voltage spikes caused by collapsing magnetic fields when current through the relay is shut off.

What happens to terminal 87a when a 5-terminal relay is energized?

When the relay is energized, terminal 87a loses power as it switches to supply power to terminal 87 instead.

What should you consider when selecting wire gauge for a relay installation?

You should consult an automotive amperage chart to determine the appropriate wire gauge based on the load and the length of the wire needed for installation.