A car relay is like a helper that turns important parts of your car on and off, like headlights or the fuel pump.
In this article, you’ll learn all the basics about car relays.
Table of Contents
What is a Car Relay?
A car relay acts as a switch, allowing the vehicle to control high-power devices like the headlights, fuel pump, or electric fans without running a high current through the less powerful switches and circuits.
Think of it as a tiny traffic cop for electricity, making sure power goes where it’s needed.
In simple terms, a relay uses a small current to control a larger one.
It’s not uncommon for a new car or truck to have 20 relays.
When you turn on a device in your car, the small control current passes through a coil inside the relay. This generates a magnetic field, causing an internal “lever” to switch on, and allowing the larger current to flow through the device. As a result, devices like headlights, electric fans, or fuel pumps are safely and efficiently powered.
What Does a Car Relay Look Like?
A car relay is a small, rectangular or cube-shaped electrical component with multiple terminal connectors at the bottom.
The casing is often made of a durable plastic material, and the color is often black or transparent.
Relays usually have visible markings on the top or side to indicate their specifications, such as:
- the voltage rating,
- current rating,
- and sometimes a diagram showing the internal connections (commonly labeled as coil and contact points).
Do All Cars Have Relays?
While all modern cars have relays, older cars often rely on more basic electrical systems instead of relays.
If you’re unsure whether your car has relays or not, a good place to check is the owner’s manual for your vehicle. This document will always provide information about the electrical components in your car, including the presence and location of relays.
You can also locate the fuse box in your car, which often contains both fuses and relays. Look for small, box-like components with sockets to be plugged in. These are your relays. See more below about where the relay may be located.
Where is the Relay Located in a Car?
Relays are typically found in your vehicle’s fuse and relay panel, either within the engine compartment or inside the cabin.
Once you’ve found the junction box, locating the relay inside it should be relatively easy. Sometimes, it might be necessary to remove other parts for easier access; refer to your car’s manual for guidance on whether this is needed for your vehicle.
How Long Does a Relay Last?
A car relay will typically last as long as the car. It’s common for a car relay to last at least 15 years or 150,000 miles.
However, you will need to monitor the car relay if you experience premature blown fuses or if the car has had an accident.
How Much Do Car Relays Cost?
For more common, less specialized relays, such as those used for horns or windshield wipers, you might expect to pay anywhere from $5 to $20.
Mid-range relays for slightly more complex systems, like fuel pumps or cooling fans, the price could range from $20 to $50.
Specialized or High-Performance Relays for high-end or luxury vehicles, or for relays designed for specific, high-performance applications, the cost can go even higher—potentially over $100.
|New Relay||$50 to $250|
|Scrap Yard||$10 -$100|
Take your time to find the best option that suits your budget and your car’s requirements.
Keep in mind that you want to prioritize quality while also keeping an eye on the price to ensure you’re making a wise investment. Good luck finding the perfect relay for your vehicle!
How Much Does it Cost to Replace a Relay in a Car?
Labor costs for relay replacement generally range between $50 and $120.
The specific amount will depend on factors like the type of relay, your vehicle’s make and model, and how accessible the relay is.
What Happens When a Relay Malfunctions?
If a relay starts to fail, you may experience weakened or intermittent power to the unit it controls.
- For example, a faulty headlight relay may cause flickering or dimming lights.
- A bad A/C compressor relay may result in inconsistent A/C performance.
- A malfunctioning cooling fan relay can cause your engine to overheat due to ineffective fan operation.
- If your car’s engine cranking circuit relay fails, you might find that the engine cranks but does not start.
This happens because the relay compromises power to the engine control computer necessary for ignition.
Can You Continue Driving with a Faulty Relay?
Whether you can keep driving with a faulty relay depends on that relay’s function.
For instance, if you have a faulty headlight relay, it’s not safe to drive at night. However, you may still be able to drive during the day with caution.
On the other hand, if you have a malfunctioning cooling fan relay, you risk damaging the engine due to overheating if you continue driving. Therefore, driving without a properly functioning relay is generally not recommended.
Can You Replace a Car Relay Yourself?
Yes, you can replace a car relay yourself with a little bit of knowledge and some basic tools.
First, turn off the ignition and ensure the key is in the off position. Carefully remove the faulty relay, noting its orientation.
This is important because you’ll need to install the new relay in the same position.
Now, insert the new relay and make sure it’s aligned correctly.
Once the new relay is installed, you can turn on your car’s ignition to test the functionality of the affected circuit.
In most cases, replacing a car relay is a simple and straightforward process.