Replacing Headlights on a 2016 Scion iM: What Actually Works
I replaced my own headlights on a 2016 Scion iM last spring. The driver side was clouded enough that I could barely see the road at night past the intersection near my apartment. The passenger side wasn't great either. You probably know how this goes. You look in the mirror and wonder what took you so long to notice it was this bad. This guide covers the actual steps I took, the parts I used, and the things I wish someone had told me before I started. There are two main approaches here: restoring the existing lens or replacing the whole assembly. I went with restoration on both sides. Replacement is simpler if you can afford it, but the cost adds up fast. The headlight housings on the Scion iM use halogen bulbs behind a plastic polycarbonate lens. Over time, UV exposure breaks down the clear coat on the outside of that lens. Once it cracks, water and oxidation get inside. Sanding it off and applying a new protective layer is the restoration route. Replacing the whole unit means buying new assemblies, which run anywhere from eighty to two hundred dollars each depending on whether you go aftermarket or OEM.
I used a three-inch microfiber pad, a drill, and a progression of sandpaper starting at 800 grit and moving through 1500, then 3000. For sealing, I applied a UV-resistant clear coat spray. The whole process took about forty-five minutes per side. Not fast, but manageable if you're methodical. Here is how it actually goes down. First, you need to remove the headlight assembly. On the 2016 iM, this means taking out three 10mm bolts on the top, two on the side near the fender, and disconnecting the electrical connector from the back of the housing. The connector is a simple plug type. Press the tab and pull. No tricks there. Once the assembly is out, mask off the surrounding paint with painter's tape and a plastic sheet. Getting sandpaper residue on your bumper paint is a real pain to clean up. I learned this the hard way on a previous car.
Start wet sanding with 800 grit. Keep the surface wet the entire time. Use a spray bottle with a little dish soap in the water. Sand in straight lines, not circles. Circles create swirl marks that show up later when you apply the clear coat. Move through 1500, then 3000 grit. Each stage removes the scratches from the previous one. This takes patience. I spent roughly twenty minutes on the driver side total for all three stages. After the final sanding stage, the lens should look uniformly matte. If you still see glossy patches, those are areas you missed. Go back over them. This step matters more than anything else. A poor sand job means the clear coat will peel or look uneven within months. Clean the lens thoroughly with isopropyl alcohol. Any residue left from sanding or soap will prevent the clear coat from bonding properly. Wipe it down, let it air dry, then spray on two to three light coats of UV-resistant automotive clear coat. I used an aerosol can from an auto parts store. Don't rush this part. Wait fifteen minutes between coats. If you apply it too thick, it runs. Runs look terrible once they cure.
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Reinstall the assembly in reverse order. Tighten the bolts finger-tight first, then give them a quarter turn with a socket. Over-tightening strips the plastic threads in the housing. I've seen it happen. It's not fun to deal with. The real issue most people run into is the bulb itself. The Scion iM uses a 9005 bulb for the high beam and a 9006 for the low beam. These are standard sizes but they get hot. If you touch the glass portion of a new bulb with bare fingers, the oils transfer and create hot spots that shorten the bulb life significantly. I always use a paper towel or gloves when handling halogen bulbs. It adds ten seconds to the job and prevents premature failure. Another thing nobody mentions: the alignment. After reinstalling, you need to check your aim. There are two adjustment screws on the back of each housing. One controls vertical, the other horizontal. With the car parked thirty feet from a wall, the top edge of the beam pattern should sit at or just below the center height of the headlight. If it's pointing up, you're blinding oncoming drivers. If it's too low, you're not seeing far enough ahead. Mine were slightly off after reinstallation. Took about five minutes to dial them in with a Phillips screwdriver.
One edge case I encountered that I didn't expect: the plastic clips holding the lower splash shield came loose during removal. Two of them snapped when I pried the fender liner away. I used zip ties as a temporary fix since the clips weren't structural. They held fine. But if you're doing this in cold weather, the plastic becomes brittle. Warm the area with a heat gun on low first, or expect broken clips. Clear coat longevity depends heavily on the product you use. The cheap aerosol cans from the auto parts aisle typically last about a year before the UV protection degrades again. I later switched to a ceramic coating spray specifically designed for headlights, and that lasted closer to three years on the driver side. The passenger side gets more sun exposure since it faces south in my parking spot, so it degraded faster regardless. If you're in a sunny climate, invest in the ceramic coating from the start. It costs about thirty dollars more but saves you from redoing the job every twelve to eighteen months. If your lens is cracked or has deep scratches that go through the original clear coat layer, restoration won't help. Sanding those out removes too much material and distorts the light pattern. In that case, replacement is the only option. I found used assemblies on eBay for around seventy dollars each, and they had decent clarity. Aftermarket new assemblies run about one hundred twenty dollars. OEM parts from the dealer are over two hundred dollars and usually unnecessary unless you want the exact factory look.
The process itself is straightforward. The challenges are in the details. Wet sanding technique, proper cleaning before clear coating, correct bulb handling, and accurate alignment are where most people cut corners and end up disappointed. Take your time with each step. The difference between a job that lasts three years and one that looks acceptable for six months comes down to how carefully you sand and seal. Tools needed: drill with variable speed, three-inch microfiber polishing pads, 800/1500/3000 grit wet sandpaper, spray bottle, dish soap, isopropyl alcohol, painter's tape, plastic sheeting, UV-resistant clear coat or ceramic headlight coating, 10mm socket set, Phillips screwdriver, 9005 and 9006 bulbs, paper towels or nitrile gloves. Total time for both sides: roughly one and a half to two hours depending on experience level. Cost for restoration materials: around twenty to thirty dollars. Cost for replacement assemblies: seventy to two hundred dollars each.
If you take photos before you start, it helps with reassembly. The wiring harness routing on the iM isn't complicated, but having a reference image prevents guessing later. I don't usually document my work unless I'm writing a guide, but this was one of those jobs where I wished I had taken a picture of how the connector sat in the bracket.
