Yes, they CAN work without one, but it is hard on the switch. Yes, you can get a relay for about $5 at most autoparts stores in the lighting section.

To activate the front fog lights, turn on the parking lights or the low beam headlights and push the headlight switch. To turn off the front fog lights, either push the headlight switch a second time or turn off the headlight switch.

Splice a red wire from the headlight wire to the relay terminal “30.” This line needs a 10-amp inline fuse, so be sure and wire one in. The final terminal on the relay is numbered “87.” This terminal will carry power to the fog lights.

A relay is an electrical switch that lets a low current circuit control a high current circuit such as a large LED light bar. If you are using a light pod that does not have a very large amp draw, you may not need a relay switch, but if you are using a larger LED light bar, they are a must have.

Relays can be used to switch a low-current trigger to high current, switch a circuit on or off, reverse polarity, and much more. When adding LED lights, such as off-road light bars, driving/work lights, or other auxiliary lights to a vehicle, you must add a circuit to power the light adequately.

85 will be used to ground your relay, while 86 will be connected to the switchable power. 87 and 87a will be connected to your controlled accessories that you wish to turn on and off with your relay.

On a relay, pins 85 and 86 get connected to your switched source and a ground, it doesn’t matter which one, since what you are powering is a coil inside the relay, which when powered magnetizes and pulls the relay.

The excess heat will melt the box, making it impossible to have your light bars on without replacing it. One wire that comes out of the relay box is the ground wire. If it is, the wire will not make a solid contact with the metal, and it would be as if you did not have a ground wire attached.

The second pin, or ground is the housing which must be mounted direct to chassis or otherwise grounded. If your relay is in a plastic housing it will have 2 pins for the coil, usually reversible. Your toggle switch is breaking the 12v power line between one side of coil and power.

Relay circuit symbol The most widely used format shows the relay coil as a box, and the contacts are placed close by as shown below. Note that on this symbol, both normally open and normally closed contacts are shown. Where one or more sets of contacts is not used, it is often not shown.

Relays are often used in circuits to reduce the current that flows through the primary control switch. A relatively low amperage switch, timer, or sensor can be used to turn a much higher capacity relay on and off. Another primary use for relays is when upgrading to halogen headlights on an older car.

The only thing they have in common, absolutely certain and guaranteed, is that they have 5 pins. Though it is likely, but not absolutely guaranteed, that 2 of these are the coil and the 3 others are the common, normally-closed, and normally-open contacts of a single-pole double-throw switch.

5 pin relays provide 2 pins (85 & 86) to control the coil and 3 pins (30, 87 & 87A) which switch power between two circuits. They have both normally open and normally closed connection pins. When the coil is activated, power will be switched from the normally closed pin to the normally open pin.

Relay coils produce brief high voltage ‘spikes’ when they are switched off and this can destroy transistors and ICs in the circuit. To prevent damage you must connect a protection diode across the relay coil.