The 4th Brake Light Module for the 2015–2023 Ford Mustang adds a center-mounted brake light while also upgrading the factory reverse light to a bright white LED and adding a red running light function at night. Plug-and-play design integrates directly with the factory wiring — no cutting or splicing. Here's how to get it installed.
Watch the full install video below, or scroll down for the step-by-step written guide.
Table of Contents
- Installation Video
- Tools Required
- Installation Instructions
- Questions About the Install?
- Shop Mustang Lighting at Ess K Customs
Installation Video
Tools Required
- Trim or panel removal tool
- Small screwdriver (included with kit)
Time Required: Approximately 30–45 minutes.
Installation Instructions
Step 1 — Open the trunk and remove the plastic liner by taking out the four screws securing it to the back of the trunk. Pull straight up and out to remove the liner, then remove the trunk floor liner and set both aside.
Step 2 — Remove the plastic locking screws from the factory liner to access the tail light connectors on both sides of the vehicle.
Step 3 — Unclip the factory tail light connector and install the first 4th Brake Light Module connector inline. Route the second module connector to the opposite side and install it inline with the other tail light.
Step 4 — Route the remaining red wire out of the vehicle using the factory grommet at the bottom of the trunk. Gently push the grommet aside and feed the wire through until there's no slack.
Step 5 — From underneath the vehicle, unplug the factory reverse light bulb by turning it counterclockwise and pulling straight out. Depress the tab to remove the bulb holder.
Step 6 — Using the included screwdriver, push the green rubber seal out of the center socket on the bulb connector to allow installation of the new terminal.
Step 7 — Insert the terminal on the end of the red wire into the empty center socket from the back of the connector. The terminal should click into place securely.
Step 8 — Remove the factory bulb from the holder and install the new LED bulb. Plug the bulb holder back into the socket and reinstall the reverse light assembly. Secure all wiring, reinstall the trunk panels, and fasten everything using the original hardware. The install is complete.
Questions About the Install?
If you run into any issues during the installation, contact Ess K Customs — as an authorized Diode Dynamics dealer, we're here to help.
Shop Mustang Lighting at Ess K Customs
Ready to upgrade your Mustang's rear lighting? As an authorized Diode Dynamics dealer, Ess K Customs carries genuine products with full manufacturer warranty.
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This install guide applies to Diode Dynamics SKU: DD3017