Ever wonder how electricity runs through your vehicle? Yes, your car comes with switches that make using those electrical auto components easy. But do you know what makes all these switches work? Their corresponding relays, of course.A relay is, essentially, a switch in itself. The relay's interior features a coil of wire wrapped around an iron core, an armature, and a set of contacts. Working together, these components allow you to use a minimum amount of power to activate a larger power source.So when one of your vehicle's relays becomes faulty, you experience power loss and the inability to control various parts of your vehicle. That's why it's recommended to replace a relay once it starts to show signs of malfunction.Don't worry; Carpartss is here to lend you a hand. This online auto part store holds a vast collection of auto parts for any car make and model. Here, you can easily find the relay that best fits your vehicle.
• Our relays are designed to resist premature wear and tear.
• All the relays we offer are tested for safety and durability.
• All our relays are crafted according to OE specifications.
Relay Buyer’s Guide
- A relay is a small electrical device that can switch various circuits on and off simultaneously. A single vehicle usually has around 20 relays powering different systems.
- Most automotive relays are designed to improve power delivery, maximize performance, improve energy efficiency, and prolong the life of car components.
- Two of the most important relays in your vehicle that can have a major impact when damaged are the fuel pump relay and starter relay.
- To tell if a relay has gone bad, you can swap it with a similar working relay or test it using a special relay tester or digital multimeter.
- Since automotive relays vary widely in terms of application, they also have a wide range of price.
- You can buy a relay for as low as $5 for a generic multi-purpose relay or as much as $350 for a complex, direct-fit relay
- A starter relay costs around $20 to $80 while a main relay costs around $20 to $200.
What is a Relay?
A relay is a small electrical device that acts like a switch. Relays are powered by electricity which it uses to switch various electrical circuits on and off at the same time. Relays in automotive applications are generally used to automate the power distribution process and switch multiple circuits on or off, including those with different voltage types, at the same time.
How a Relay Works
There are a wide range of relays available for different applications, and the specifics of how each relay works can vary. Here’s the most basic explanation of how a relay works.
Generally, an automotive relay has an electromagnetic coil, a switch, and a spring. The spring is there to hold a small metal arm up and keep the switch in an open position. In this position, when the relay is at rest, the component that is powered by the relay, say the headlights, are off. When power is supplied to the coil, it produces a magnetic field that moves the metal arm down closing the switch. In this position, when the relay is energized, the headlights are turned
Each relay in your car has a certain number of contacts or switches which allows it to control various circuits on and off.
What Does a Relay Do?
Relays can do a wide range of things depending on their specific application. Generally, the main purpose of a relay is to take a heavy load, ground it, and distribute that power to other locations.
For automotive relays, aside from switching a high current circuit using a low current circuit, most relays are also meant to:
- Improve power delivery and maximize efficiency
- Conserve energy
- Prolong the life of various car components
The relay does these three things for various systems in your vehicle. To understand how a relay does these three important functions, you need to be familiar with voltage drop. Long wires create a lot of resistance and reduce the amount of voltage and current that are delivered from the power source (such as the battery) to any particular component. Placing a relay near the source and the component reduces voltage drop. This helps your component get the exact amount of voltage they need to ensure maximum power and efficiency. By making sure that they get the right amount of power they’re rated for, relays also help conserve energy and prolong the lifespan of the different automotive components that rely on them.
Lastly, relays can also be used to control different devices using a single switch. This makes certain automotive functions a lot safer and more efficient.
Types of Car Relays
There are usually up to 20 relays in every vehicle. Each of these relays have specific functions. There are relays that operate your car’s headlights or your air conditioning system. There are relays that operate the windows or door locks. Two of the most important relays in your vehicle that can have a major impact when damaged are the fuel pump relay and starter relay.
The fuel pump relay, also called the main relay or main fuel pump relay, controls the entire fuel system of your vehicle and the computers too. When this component gets damaged, you won’t be able to drive your car at all.
The starter relay, or ignition relay, on the other hand powers your vehicle’s ignition system, and in some cases, some components of the fuel system as well. Like with the fuel pump relay, a damaged starter relay will keep your vehicle from running.
Most car relays work with a 12v signal which is standard for car batteries or a 5v signal which is standard for car sensors. Most relays are multi-purpose relays, so they can be used interchangeably with other relays in your car provided that they have the same configuration.
How to Tell if a Relay is Bad
The easiest way to tell if a relay has gone bad is to swap it with a working relay. As mentioned above, some relays in your vehicle are interchangeable, so you can get a working relay with the same configuration and replace the suspect relay with it.
Another way to test if your relay is bad is by using a special relay tester or a more generic digital multimeter tester. These devices are easy to use just by following the instructions that come with the tool. Don’t forget to give the relay a visual inspection first before testing it. If the relay shows signs of corrosion or overheating, you already know that they are damaged.
You can also look for symptoms of failing automotive relays. Of course, since different relays power different components, the symptoms will vary depending on which relay is failing.
Symptoms of a Bad Relay
Common symptoms of a bad starter relay include difficulties with turning the ignition on or off or failure to start the vehicle on some occasions. Sometimes, a bad starter relay can also produce clicking noises when you try to start your car. Sudden stalling while driving your car can also point to a damaged ignition relay.
The signs of a failing fuel pump relay are largely similar to the symptoms of a bad starter relay. A vehicle that sometimes starts and sometimes doesn’t and engine stalling problems are two symptoms they have in common. Another usual sign of a bad fuel pump relay or main relay is a fuel pump that makes no noise at all when the ignition is switched on.
When any of your other car components are failing, it’s always a good idea to check if the relevant relay is damaged or not.
How Much Does a Replacement Automotive Relay Cost?
Since automotive relays vary widely in terms of application, they also have a wide range of price. You can buy a relay for as low as $5 for a generic multi-purpose relay or as much as $350 for a complex, direct-fit relay. A starter relay costs around $20 to $80 while a main relay costs around $20 to $200.
To make sure that you’re getting the exact replacement relay you need, it’s important to consult your vehicle’s owner’s manual before shopping for replacement parts.
The Various Relays in Your Car
You can't count just how many relays there are in your vehicle because of their great number. You have relays controlling the safety features in your car (the ABS system, the airbags, and the anti-theft alarm), your various car lights (the headlights and fog lights, as well as the turn signals and the parking lights), and other basic functions that enable your car to run well (glow plugs and cruise control). All of these relays work the same way, only they power different parts.
Two General Types of Relay
Although there are different relays in your vehicle, these parts can only be generally categorized into two, as follow:
What it is: This is a relay that receives low voltage signal across its terminals and then converts the fluctuations created by such signals into a mechanical force that actuates the relay's electrical contacts.
Advantages: This type of relay is relatively cheap. Using it is also easy, so there's no hassle involved.
Disadvantages: This relay is mechanical in nature, and it is that which serves as its weakness. It doesn't respond as quickly and it may have a shorter life because of its wear components.
Solid State relay
What it is: This relay operates in the same manner, only that it isn't mechanical in nature. It is purely electrical, and it is composed of a transistor instead of moving parts.
Advantages: This type of relay has faster response time. It is also highly reliable, and it generally features a longer service life.
Disadvantages: Despite the many benefits, the solid state relay also has some disadvantages. One of the most common is its susceptibility to overheating.
Under these two general types of relay, there are still other relay designs, some of which are in popular use today while others have already become rare. If you're looking for a new relay for your vehicle, you might want to consider the different types available. Find one that is compatible with your vehicle make and model to ensure efficient function.
Automotive Relay Replacement
Can you count the exact number of relays that you have in your vehicle? Chances are, you can't-they're just too many to count. Majority of the electrical components in your vehicle are operated by a relay: the starter, the headlights, the fuel pump, and many other components. It is the relay that controls the electrical signals that get into these components so that they can work well. Once the relay is damaged, your crucial car components won't function at all. Good thing it's easy to replace the relay.
Difficulty Level: EasyTools You'll Need:
- Test light
- Flathead screwdriver
- New relay
Step 1: Disconnect the battery for safety precaution before starting the process.
Step 2: Find the relay to replace. Depending on your vehicle and depending on the type of relay, the location may vary. Possible locations are the fuse box in the engine compartment or behind the dashboard near the steering wheel. If you're not sure of the location, check your vehicle owner's manual.
Step 3: Depending on the type of relay, you may find that it is held in place by a bolt or that it simply connects like a plug. In case it's held by a bolt, you will need a wrench to unbolt it. Otherwise, you can pry it out using a flathead screwdriver. There are set-ups where you may need to disconnect a fuse and a connector before you can completely take the relay off.
Step 4: After the removal process, all you need to do is to mount the new relay the same way the old one is mounted. Then, reconnect your vehicle battery and test the component that the relay controls to see whether it's already working well.
With a new relay mounted, you're ready to drive without hassles again.