If you are upgrading your car’s lighting system or installing a new set of fog lights, then you’ll need to do some wiring. The proper wiring of the lights can mean the difference between a successful installation and a dangerous electrical catastrophe. One of the essential parts of your lighting setup is a relay, which helps to switch the lights on and off. In this article, we’ll discuss how to wire 4-pin relays for fog lights.
What is a Relay?
A relay is an electrical switch that allows a low voltage electrical signal to control a high voltage electrical signal. It works by using a small amount of power to switch a larger load on and off. In the case of fog lights, the low voltage electrical signal is usually the power coming from your car’s light switch, and the high voltage load is the power going to the fog lights.
There are many different types of relays, but the most common for fog lights is the 4-pin relay. The four pins are typically labeled as follows:
| Pin | Label |
|---|---|
| 30 | Battery |
| 85 | Ground |
| 86 | Trigger |
| 87 | Load |
Wiring a 4-Pin Relay for Fog Lights
The wiring process for a 4-pin relay used for fog lights is pretty straightforward. Here are the steps:
Step 1: Mount the Relay
The first step is to mount the relay somewhere in your engine bay. Make sure it’s somewhere secure and won’t be affected by water or heat. You can use a relay holder to keep it in place.
Step 2: Wire the Battery Connection
The next step is to connect the positive wire from your fog lights to pin 87 on the relay. This pin is labeled as “Load.” Once you’ve done that, connect the other end of the wire to your car’s battery. You can use a fuse to protect your wiring from any electrical shorts.
Step 3: Connect the Ground Connection
Now, you need to connect the negative wire from your fog lights to pin 85 on the relay. This pin is labeled as “Ground.” Make sure it’s connected to a good chassis ground or the negative terminal of your battery.
Step 4: Connect the Trigger Connection
The trigger connection is where things get a little more complicated. This is the pin that turns the relay on and off. You need to connect this pin to the wire that will trigger the relay, which is usually the wire that runs from your car’s light switch to the fog lights. This wire should be connected to pin 86 on the relay.
Note: If you are using a switch to control your fog lights instead of your car’s light switch, you will need to connect the switch’s output to pin 86 on the relay instead.
Step 5: Connect the Power Connection
The last step is to connect the power wire to pin 30 on the relay. This pin is labeled as “Battery.” This wire should be connected to a power source that is always hot, which means it’s connected directly to the battery. You can use a fuse to protect your wiring from any electrical shorts.
FAQ:
What is the purpose of a 4-pin relay in fog lights?
A 4-pin relay is used to control the power going to the fog lights. It allows a low voltage electrical signal to switch a higher voltage load on and off, which helps to protect your car’s wiring from electrical shorts and overheating.
What is the difference between a 4-pin and 5-pin relay?
A 4-pin relay is typically used for simple wiring setups, like fog lights, where there is only one trigger wire. A 5-pin relay is used when you need more complex wiring, like for dual-filament bulbs, where you need two trigger wires.
Can I use a 4-pin relay for headlights?
No, a 4-pin relay is not suitable for headlight wiring because it doesn’t have enough pins to control high and low beams. You should use a 5-pin relay or a dual-relay setup for headlight wiring.
What size fuse should I use for my fog light wiring?
The size of the fuse you should use depends on the wattage of your fog lights. As a general rule, you should use a fuse that is rated 10% higher than the total wattage of your fog lights. For example, if your fog lights are 55 watts each, you should use a 12V 110-watt fuse.
Can I wire my fog lights to my high beams?
No, it is not legal to wire your fog lights to your high beams because it can blind oncoming drivers. You should wire your fog lights to your low beams or add a separate switch to control them.
