When you order a complete HID bi-xenon projector retrofit kit, that box arrives packed with more parts than a lot of first-time builders expect. We shot this walkthrough on the bench so we could physically pull every piece out and explain exactly what it does before you ever open your headlights. Understanding these HID projector retrofit kit components ahead of time makes the actual install far less intimidating, and it helps you spot anything missing before you start cutting into a housing. Below, we break down every core component, the optional add-ons, and how the bi-xenon pieces differ from a low-beam only setup.
The Projectors: The Heart of the Kit
The first thing we pull out of any complete kit is the pair of projectors. This is obviously the main component, so you get two boxes, a matched pair. In this case we were working with a set of bi-xenon projectors, and every bi-xenon projector will have wires coming out of the bottom. When you mount them, you always want to make sure the solenoid sits on the bottom so the high-low mechanism functions correctly once everything is buttoned up.
Another key feature of the projector is the bulb holder. This is where the bulb seats, most commonly either D2S or H1 depending on your projector. In this setup we used D2S. The holder has little clips built into it, and you insert the bulb from the back so those clips lock it into place. It is a simple mechanism, but it keeps the bulb square and secure.
What Makes a Bi-Xenon Projector Different
If you are getting a bi-xenon projector, you will also find a clip and two rubber seals in the box. Those seals get installed on the ends of the two metal pins on the projector. Those pins serve as the input for the bi-xenon solenoid, and that solenoid is exactly what creates the high-low beam function. You only get those pieces if the projector is a bi-xenon unit. For low-beam only projector kits, like those built for a TSX or an RX330, you will not have that solenoid or that high-low function in the wires at all, so there is nothing to worry about on that front.
If you are still shopping and comparing options, our lineup of Universal Projector Retrofit Kits is a good starting point for matching a bi-xenon projector to your application. Enthusiasts who want to dig into a specific projector like the Morimoto Mini D2S 5.0 bi-xenon projector can see how those same bi-xenon principles carry across different models.
The Ballasts: Powering the Xenon Arc
The second component you always get with a complete retrofit setup is a set of ballasts. In this kit we were looking at the Morimoto 35W ballasts, and each one comes in its own box with some packaging. This particular ballast is made for D2S, so it has the P32D connector on it. That connector is what goes to the bulb. On the other side is the input for the ballast, which connects to the output from your wire harness.
Along with the ballast itself, you get some mounting hardware: a mounting bracket that attaches to the back of the ballast and the screws to secure it. There is also one part that confuses a lot of people. It is a basic pigtail with two wires on one end and a 9006 connector on the other. This is a test lead for the ballast. You are not going to use it in the final installation. It exists purely so you can test fire the ballast with direct power from the car battery to confirm it works before you commit it to the build.
If you want to understand how these ballasts stack up against other options on the market, our overview of aftermarket HID ballasts covers the differences in build and connector types you will run into.
The Bulbs: Handle With Care
The third core component is a set of bulbs. Since the projectors in this kit use D2S, D2S bulbs are what came supplied. They always arrive in a box, and inside that box they are usually protected in a plastic bulb cup. To get them out, we carefully remove them from the cup and take all the packaging away until we are left with just the bulb itself. The bulb has a return wire on it that goes into the projector, and just like the solenoid, that wire always faces the bottom.
One thing we cannot stress enough is that the bulb must be mounted straight and not crooked. If it goes in at an angle, that misalignment will have a negative effect on the light output, and you will end up with a beam pattern that does not look right. Take your time and make sure it seats squarely in the holder.
The kit also includes a set of alcohol wipes, and these are not an afterthought. You use them to clean the bulbs before you install them for the final time. Wiping them down removes fingerprints, dust, grease, and dirt, all of which can shorten a bulb’s lifespan or cause hot spots. A quick clean before final assembly is cheap insurance for the life of the bulb.
The Shrouds: Finishing the Look
Every kit is completed with a set of shrouds, which you will have selected during ordering. Here we were looking at the Apollo shrouds, one of the more popular choices. It is a fully circular shroud that covers the projector nicely. The shroud goes over the projector when you are mounting it into the headlight, giving the front of the projector a clean, finished appearance behind the lens.
The Apollo shrouds come with centering rings, which act as the adapter flange between the back side of the shroud and the front of the projector body. These rings snap into the back of the shroud, using the little dimples and clips integrated into both the centering ring and the shroud. Once that is snapped together, you snap the assembly onto the front of the projector, and that serves as the connection point. A lot of people skip glue here because the shroud tends to stay on with friction alone, but we always recommend adding glue between the pieces. Road vibration and heat over time can work a friction-fit shroud loose, and a little glue prevents that from ever becoming a problem.
The Wire Harness: Making It All Work
The last major component that comes with every retrofit kit is a wire harness. In this case we had the Morimoto controlled bi-xenon harness. These always have anodized junction boxes, and the color can vary depending on the application. This is where the difference between a bi-xenon and a low-beam harness really matters.
A low-beam wire harness looks a little different because it has two independent relays. You would get that style if you were running something like a 9006 or an H7 setup. With a low-beam harness, you also get high beam splitters, and you need those splitters to activate the bi-xenon solenoid on the projector when your kit is a bi-xenon setup. However, with a true bi-xenon relay harness like this one, the harness handles all of the high-low switching for you automatically, so you do not need the high beam splitters at all.
Getting the harness right is one of the most common places builders trip up, so if you are unsure which style fits your vehicle, read our guide on choosing the right HID relay harness. For multi-projector builds, the Quad Bi-Xenon Wiring Kit is worth a look when you need to power four projectors cleanly. And for a broader perspective on how kits are assembled across the industry, Headlight Revolution’s projector retrofit kits offer another reference point.
Optional Components: Angel Eyes and Resealing Glue
Beyond the core parts, there are a couple of optional items you may or may not have selected. The first is angel eyes. Here we had the XB LED angel eyes, which are very popular. They come in a box with two rings inside, along with a little note telling you who inspected the LEDs and some basic information about them.
With the XB LEDs, you get the ring itself, which mounts to the front face of the shroud (we have separate mounting instructions for that step). You also get a pigtail and the LED driver. The driver supplies and regulates power to the ring, and the pins on the end are what you feed power through. It is a simple setup, just positive and ground, so wiring the angel eyes in is one of the easier parts of the whole build.
The last optional item is resealing glue. This is great for resealing the headlight housing after you have finished your work inside. It comes in a roll, and when you go to reseal, you unroll it and lay it into the channel that separates the front and back halves of the housing.
A lot of times the glue is a little thick, so when that is the case, we recommend stretching it out slightly. That thins it just enough to fit properly between the two halves of your housing. It is not required in every case, but it is helpful to have on hand for a clean, sealed reassembly.
Putting It All Together
When you lay out a complete kit on the bench, the picture becomes clear: projectors, ballasts with hardware and a test lead, bulbs, alcohol wipes, shrouds with centering rings, and a wire harness are the core pieces every retrofit needs. Add in optional angel eyes and resealing glue depending on what you selected, and you have everything required to transform a set of headlights. Knowing what each component does, and understanding how the bi-xenon parts differ from a low-beam setup, is the difference between a smooth install and a frustrating one.
Frequently Asked Questions
What are the main components included in a complete HID projector retrofit kit?
A complete kit includes a pair of projectors, a set of ballasts with mounting hardware and a test lead, a set of bulbs, alcohol wipes, shrouds with centering rings, and a wire harness. Optional items like angel eyes and resealing glue may also be included depending on what was selected.
What is the difference between a bi-xenon and low-beam only projector?
Bi-xenon projectors have a clip and two rubber seals installed on metal pins that serve as the input for a solenoid, which creates the high-low beam function. Low-beam only projector kits, like those for a TSX or RX330, do not have this solenoid or visinon function.
What is the test lead included with the ballast used for?
The pigtail with two wires and a 9006 connector is a test lead for the ballast. It is used to test fire the ballast with direct power from the car battery and is not meant to be used in the final installation.
Why are alcohol wipes included in the kit and how are they used?
Alcohol wipes are included to clean the bulbs before final installation, removing fingerprints, dust, or grease to help ensure the bulbs’ lifespan.
What is the purpose of the resealing glue included in some kits?
The resealing glue comes in a roll and is used to reseal the headlight housing between the front and back halves. It is often thick, so stretching it slightly helps it fit properly between the two housing halves, though it is not required in all cases.
Meet the Experts Behind The Retrofit Source
Tyler Jordan – Technical Writer
Tyler works directly with the TRS product R&D team, bringing over a decade of automotive aftermarket lighting experience to every article. An avid enthusiast with hundreds of personal installations under his belt, his content is built on hands-on knowledge from the workbench, not spec sheets.
Caleb Morgan – Marketing Manager
Caleb brings over a decade of automotive lighting industry experience and works with TRS customers daily on the front lines. With hundreds of personal lighting installations and a direct feedback loop from real buyers, his content addresses the questions and problems that actually matter.
