Fits: 2015-2017 Ford Mustang S550 pre-facelift — V6, EcoBoost, GT and Shelby. Works with both stock halogen reflector and factory HID projector headlights.
This is the pre-facelift car only. The 2018-2023 facelift uses a different headlight and a different bumper teardown — see the 2018-2023 Mustang headlight guide.
These steps cover both builds, Clear and RGB. Removal and fitting are identical; the RGB build has an extra app setup section at the end.
The front bumper has to come off. Nothing in the job is difficult, but the bumper is held from above, below and inside both wheel wells, so give yourself time and keep the hardware sorted.
This generation uses two supplied adapter harnesses — one for the sequential turn signal and one for the side marker light. Find both in the box before you start.
Before You Start
- Park on level ground, switch off, and disconnect the negative battery terminal while handling wiring.
- You will need to raise the front of the car safely to reach the underbody shield.
- Use masking tape along the fender and hood edges so nothing gets scratched.
- Do not put dielectric or weather-sealing grease on connectors or sockets.
- Leave the bumper and shield off until every function has passed testing.
Required Tools
- Trim removal tool or panel clip tool
- Metric socket and ratchet set, including 7 mm, 10 mm and 13 mm
- Phillips and flat screwdrivers
- Jack and jack stands
- Masking tape and clean microfiber towels
- Electrical tape and zip ties for the supplied harnesses
- A flat wall for beam aiming
Part 1: Remove the Front Bumper
Step 1: Remove the Radiator Support Fasteners
Remove the upper engine bay plastic cover if fitted, then remove the screws securing the bumper to the radiator support.
Step 2: Remove the Underbody Shield Fasteners
Raise the front of the car safely, then remove the screws and retaining clips securing the lower shield.
Step 3: Release the Wheel Wells
Remove the retaining clips from the wheel-well liner and pull the liner aside. Inside the joint between the fender and the bumper there is a 7 mm screw — remove it on both sides.
Step 4: Take the Bumper Off
Carefully release the bumper side tabs from the fenders, lift the bumper, disconnect the marker light wiring harness underneath, and remove the bumper. Lay it on cardboard or a mat.
Part 2: Remove the Factory Headlights
Step 5: Remove the Three Headlight Bolts
Each headlight is held by three bolts: one 13 mm and two 10 mm.
Step 6: Pull the Headlight and Unplug It
Press the metal retaining clip, gently wiggle the headlight out, then disconnect the main power plug. Keep the factory lamp on the bench as a reference until the new one is in.
Part 3: Install the New Headlights
Step 7: Connect the Turn Signal Adapter Harness
Connect the yellow wire harness from the new headlight to the supplied adapter harness. This is what drives the sequential turn signal — skip it and the turn signal will not sweep.
Step 8: Connect and Position the Headlight
Connect the main power plug and the metal retaining clip, align the new headlight to its mounting position, and install one bolt loosely to hold it there.
Step 9: Test Now, Before You Go Further
Unlock the car and verify the startup animation, daytime running lights and turn signals all work. Catching a problem here saves taking the bumper off twice.
Step 10: Connect the Marker Light Adapter Harness
Connect the second supplied adapter harness between the factory marker light plug and the marker light.
Step 11: Secure the Headlights and Refit the Bumper
With all plugs connected, push the headlights fully back into their original positions and tighten all three mounting bolts. Reconnect the marker light plug, align and refit the bumper, then refit the fender-side screws, the lower shield screws, the upper radiator support screws and the wheel-well clips.
Before you fully tighten the top bolts, nudge each lamp until its edges line up flush with the hood and fender — that is what gives you even body gaps.
Step 12: Test Every Function
Run through low beam, high beam, DRL, parking light, left and right turn signals, hazards and the sequential sweep. Cycle the ignition twice and confirm no hyperflash or flicker. Then check the beam aim against a flat wall about 25 feet away, on level ground, and bring the cut-off line level and even across both sides.
The Clear build is now fully installed. The next section applies only to the RGB build.
RGB: Star Light Running App Setup
1. Animation control. The app controls the daytime running light animations. The startup animation is preset and cannot be changed.
2. Download the app. Search for "Star Light Running" in the App Store or Google Play, or scan the QR code on the controller box.
3. Bluetooth connection. Open the app, tap Add Device (Figure 2), open the interface (Figure 3), and select the nearby device.
4. Adjusting modes.
- Dynamic mode: the number in the center of the blue box shows the current mode. Tap + or - to switch effects, or AUTO to cycle through all of them.
- Static color: drag the color wheel in the green box, or tap a preset color. This stops any running animation.
- Brightness: drag the slider in the first row of the red box.
- Speed: drag the slider in the last row of the red box.
Tip: if you used the older "Light Running" app and have trouble connecting, use "Star Light Running", the upgraded version.
Road use. Color modes are for show and display use where permitted. Confirm that the standard road-light functions work normally before using any color mode.
Common Issues and Solutions
The turn signal does not sweep. The yellow harness in Step 7 is not connected to the supplied turn signal adapter, or the adapter is not fully seated.
The side marker does not work. Check the marker light adapter harness from Step 10, and that the marker plug under the bumper was reconnected after the bumper went back on.
One headlight does not turn on. Recheck the main connector lock and the corresponding fuse. Inspect the pins inside the connector; if any are bent, straighten them carefully and reconnect.
Swap test. If a headlight still does not work, swap the left and right units to find out whether the issue is the light or the car's wiring.
Warning, flicker or hyperflash. Confirm both supplied adapters are connected and secured before assuming a fault in the assembly.
The bumper will not sit flush. Check for a trapped harness, a broken or missing clip, or a bumper corner tab that has not fully engaged in the fender.
App cannot connect. Turn on Bluetooth and Location Services on your phone (Android needs Location for Bluetooth scanning). Keep other strong signal sources away from the car.
Condensation inside the headlight. Temperature differences can cause light condensation, which is normal. Once the light has been on for a while and the internal temperature stabilizes, the moisture clears on its own. It does not affect brightness, performance, or lifespan.
