How Do I Install a 3rd Brake Light Flasher?
If you’re wondering how to install a 3rd brake light flasher, you’re not alone. A flasher module is a simple upgrade that improves rear visibility and helps alert distracted drivers when you slow down. When installed correctly, it adds safety without changing how your brake lights function during normal driving.
This guide walks through how to install the GTR Lighting LED Brake Light Flasher Module, released in June 2015. This updated version supports more vehicles thanks to its three-wire design and works specifically with LED brake lights.
Important: Do not use this flasher with incandescent bulbs. The module supports up to 3 amps of current draw and is designed only for LED lighting.
What the GTR Lighting Flasher Module Does
The GTR Lighting flasher installs inline with your third brake light. When you press the brake pedal, the module rapidly flashes the brake light before switching to a solid output. This flashing pattern draws attention without interfering with standard brake operation.
Unlike older two-wire designs, this version includes three wires, allowing compatibility with both positive-switched and ground-switched brake systems.
Determine Your Brake Light Wiring Type
Before installing the module, you need to identify how your vehicle’s brake lights are triggered.
Use a digital multimeter or a computer-safe test and check the wiring at the third brake light:
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Positive-switched system:
The ground is constant. Power appears only when you press the brake pedal. -
Ground-switched system:
Power remains constant. Ground completes the circuit when you press the brake pedal.
Knowing this determines how you connect the flasher module correctly.
Installation Overview
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Locate the wiring for your third brake light.
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Identify the power, ground, and brake signal wires.
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Wire the flasher module inline using the included diagram.
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Secure all connections and test functionality before final reassembly.
Take your time during installation. Test the system before closing everything up to ensure proper operation.
If you’re unfamiliar with automotive wiring, we recommend reviewing our other installation guides on the Better Automotive Lighting Blog for additional context.
Compatibility Notes
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Designed only for LED brake lights
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Maximum draw: 3 amps
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Works with both positive- and ground-switched systems
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Ideal for trucks, SUVs, and vehicles with elevated third brake lights
Where to Buy
You can find the GTR Lighting Flasher Module here:
https://www.gtrlighting.com
For additional lighting upgrades and installation walkthroughs, check out related guides on:
https://blog.betterautomotivelighting.com/
To stay up to date on fog light bulb fitment, lighting upgrades, and installation guides, be sure to check back here regularly. You can also follow along on our Facebook page and say hello. And as always, the Better Automotive Lighting Blog is your source for clear, practical information in the automotive lighting world. Why not give this a read: The BEST Full LED Taillight for the 2009-18 Ram
Meet the people behind Better Automotive Lighting
John Tobias, Headlight Junkie and Industry Veteran
Before managing pricing and product categories for the DLG brands, John worked directly with customers in customer service and tech support, then spent several years in marketing creating content like this and the videos published online. Today he takes more than ten years of aftermarket automotive lighting experience to events all over the USA, meeting customers and talking to real people about what they care about. He is focused on understanding the market, the trends, the big players, and what matters to lighting enthusiasts. John has tested thousands of lights, works directly with lighting engineers to evaluate the technical performance behind every recommendation, and is one of the foremost experts on everything happening in the world of aftermarket automotive lighting. LinkedIn
