Balancing Act

DIY: How to install an HID kit on your 3rd gen Toyota Prius

No rocket science is involved when it comes to installing modern aftermarket high intensity discharge (HID) xenon kits since most contemporary kits are manufactured with updated technology, standardized and almost 100% plug-n-play. Most kits these days can be purchased for as low as $30 whereas you couldn't find a kit cheaper than  $250 seven years ago. The HID kits of yore were usually not plug-n-play, required some level of manual customization (i.e. relocating wire prongs, wire splicing, etc.), bulky in built and require additional cable / plug adapters to work with your OEM light setup. Ballasts were hard to purchase as a standalone unit back then but today you can find replacement ballast for as low as $10.00 each. Pricing point for HID replacement bulbs are no different. A pair of Xenon upgrade bulbs can be had today for as low as $10.00 while the price no less than five years ago can cost you up to $150 for a pair.

For this guide, I'll be installing the popular "eBay HID kit", Xentec HID kit onto a 2012 Toyota Prius as well as identifying the components that make up a generic aftermarket HID kit that uses AMP connectors for the bulbs. This install guide pretty much applies to older model Prius as well. Just order the HID kit with the correct bulbs and correct OEM head light adapter.

Components of an Aftermarket HID Kit

A complete HID kit will include, at minimum, the following components:

  • HID ballasts
  • HID bulbs
  • Extension cables

In a nut shell, the ballast has two cables:

  1. one input cable that is drawing power from the OEM headlight connector, converting the signal into high voltage
  2. one output cable that takes the converted signal inside the ballast and outputs the power to ignite the HID bulb

Here's a diagram of what a typical HID kit looks like:

HID kit components

HID kit components

Installation Guide

The whole installation process should take you no longer than 20 minutes; that's installing both driver and passenger side HID upgrades.

There are several areas where you can mount the ballast. You can mount the ballast underneath the headlamp and secure the ballast onto the base of the headlight with a short self-tapping screw. This route requires the bumper removed and could take 45 minutes or longer, depending on your experience. To expedite the installation, we'll mount the ballasts behind the front fender protectors inside the engine bay.

Begin the process by opening up the hood and removing the left and right inner fender protector from within the engine bay. You can work simultaneously or concentrate on one side, depending on your preference. Two clips secure each protector onto the side wall of the front fender inside the engine bay. To dislodge these clips, you'll need to pinch the retainer tabs (two per clip) to release them. I find using a pair of needle nose pliers the easiest method to remove them but you can also remove the clips using a small flathead screwdriver and maneuver the protector out. To remove the driver side fender protector, you will first need to remove the under-hood fuse box cover:

Fender protector

Fender protector

Next, remove the low-beam bulbs from their housing by turning them counter-clock wise. Release the bulb from the OEM headlight connector by pressing on the connector's retainer clip:

OEM H11 bulb removed from low beam housing

OEM H11 bulb removed from low beam housing

Set the OEM H11 bulb you've just removed aside and install the HID H11 upgrade bulb into the low beam housing. Be careful not to damage the ground-return wire as you insert it into the housing. After swapping out bulbs and having removed the fender protector, it's time to assemble the headlight power extension cable (if your kit includes one and if it's unassembled). Attach one end of the extension cable to the HID ballast:

HID ballast with extension cable attached

HID ballast with extension cable attached

The extension cable can be assembled by pushing the terminal pins from the extension cable into the provided male 9005 bulb-type connector in the correct orientation:

Ground and power terminals

Ground and power terminals

The orientation of the ground and power pin does not matter as the socket itself is reversible. As long as the pins are securely in the connector, you'll be fine.

Completed extension cable attached to HID ballast

Completed extension cable attached to HID ballast

Next, we'll attach the ballast onto the fender protector. Take the included double-sided adhesive and attach it onto the base of the ballast. The adhesive is not 3M and indicative of potentially low quality adhesion. You can discard these white foam double-sided adhesive and use strips of 3M double sided automotive molding tape for the installation or install as is. But as a warning, the engine bay gets really hot and the included white foam adhesive will not hold, that is sometime down the line, the ballast will fall off from its mounting area on the fender protector. If you insist on using the included adhesives, I advise securing the ballast with a bolt/nut or self tapping screw onto the fender protector. In either case, ensure the adhesive is attached to the ballast securely by cleaning the base of the ballast then applying a firm and even pressure across the surface of the adhesive.

Apply double-sided adhesive onto the bottom of the HID ballast

Apply double-sided adhesive onto the bottom of the HID ballast

Remove the remaining adhesive backing and attach it to the back side of the fender protector. Since we have extension cables and the output cable is long enough to reach the HID bulb AMP connector, I decided to mount the HID ballast as close to the end of the fender protector as possible. The reason is to eliminate wire clutter:

Mount the HID ballast to the fender protector

Mount the HID ballast to the fender protector

Reattach the fender protector by snapping the two clips back into their corresponding holes on the fender as you route the two cables from the ballast and underneath the front-most clip on the fender protector, then connect AMP connectors from the HID bulb to the AMP connectors on HID ballast.

AMP connectors from ballast connected with HID bulbc

AMP connectors from ballast connected with HID bulb

Plug the extension cable socket into the OEM headlight plug (the plug that was attached to the OEM H11 bulb) and then organize the wire so that they are not obstructing anything. You may use zip ties or wire looms to conceal the wires:

Connect the extension cable to the OEM headlight connector

Connect the extension cable to the OEM headlight connector

Turn on your headlight stalk to the ON position and the headlight which you've just installed the HID bulb into should fire up. If it does not light up, reverse the orientation of the extension cable plug that's connected to the OEM head light plug. If that still doesn't fire up the HID bulb, ensure that the AMP connectors are secure and check the HID bulb. If glass globe on the HID bulb appears cloudy or anything but clear, then you've got yourself a faulty HID bulb. If all else fail, you may have received a DOA HID ballast. In such an event, your option is to contact your seller and acquire a replacement ballast.

Don't forget to reattach the under-hood fuse cover after you're done working on the driver side head lamp.

Xentec 5000K HID kit installed onto a 2012 Toyota Prius

Xentec 5000K HID kit installed onto a 2012 Toyota Prius

Enjoy your new upgraded headlights! As a backup, I recommend keeping your OEM H11 bulbs with you at all time inside your car. In the event where your HID system fails, you can swap the bulbs out on the spot in less than 2 minutes and be on your merry way. You can live with one bulb going out but in the rare event that both bulbs simultaneously go out, you have a backup solution on hand. It would be really unfortunate if both lights malfunction while embarking on a road trip at night and not have spare bulbs (especially if you are traveling interstate where ordering replacement bulbs isn't really an option)! I keep all of the bulbs I've replaced in my Toyota Emergency Roadside Assistance kit stored in the sub-storage space beneath the cargo area. You're probably asking, "why not just buy a set of extra HID bulbs for back up?", and you can do that if you want. But if a ballast goes out instead of a bulb, the extra set of HID bulbs will not help. If you have a spare tire in the trunk, why not headlight bulbs?

Cutoffs and Output

For photos of light output and cutoffs, please refer to an updated entry: Update: Nokya LED projector fog lights and Xentec 5000k HID cutoffs

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