Do I Need a Relay Harness?

Some vehicle’s electrical system may require a relay harness to cars with very small gauge wiring that cannot supply the initial surge current required to light the bulbs reliably. Relay’s will resolve flickering issues and/or lights not turning on in most cases.

Symptoms indicating the relay harness is required would be intermittent starting or lights going out after being turned on and requiring you to turn the lights off and back on for them to turn back on again. The relay harness basically helps regulate the power and keep the lights on when turned to the “on” switch. If you are not sure if you need a relay for your vehicle, feel free to email us using the contact page. Although not many vehicles require a relay to work; sometimes you just never really know until you try.


A relay harness connects your HID lighting system directly to the car's battery. This allows the lights to draw power from the battery rather than the rest of the vehicle's system.

The main benefit of installing a relay harness is that it can help to provide a regulated flow of energy to your HID headlights. By regulating current and drawing power from the battery, a relay harness can help prevent damage to your HID lighting system as well as the car itself. It can also fix many common problems, such as flickering lights, headlights that don't turn on, and lights that draw too much or too little power.

Quick Q&A to determine whether or not to use a relay:

Q. Do the lights flicker on and off continuously? Yes a relay may be used.

Q. Do the lights turn on but several seconds later turn off by themselves? A relay may be used.

Q. Do the lights stay on but continuously “dance” up and down slightly? No, a relay will not solve this. A set of Can-bus ballasts usually solves this issue.

If at any given moment, your relay makes a loud buzzing sound after installation, it is either installed incorrectly or it needs to be removed.

There are also some rare cases (mostly dodge) where you will be required to use resistors alongside the relay harness. This is because when you install the HID's the voltage has been reduced and this will make the computer think there are no bulbs installed. So by taking resistors and adding them onto the HID harnesses, it can replicate the resistance needed to trick the computer into thinking there are bulbs there and that will reciprocate the flickering issue. In other words, full voltage will be supplied and you will be able to run your lights without any issues. We currently do not sell resistors. But as stated above, it is very rare when they are required and usually only is the case with Ram trucks, but not always.