The LED Flasher Module from GTR Lighting: is a simple and effective way to add safety to your vehicle! This product is designed to be used in line with an LED brake light, with power consumption not to exceed 3 amps of current draw. NOTE: DO NOT USE THIS FLASHER WITH INCANDESCENT LIGHT BULBS!: Below: you will find a wiring diagram, there are now 3 wires coming out of the switch instead of only 2. This allows the product to work on more vehicles. Depending on how your brake lights work you will need to install it one of two ways: Method 1: Positive + switched LED brake lights (most common), or Method 2: Negative - switched LED brake lights To test: whether your vehicle has positive or negative switched brake light wiring, simply use a computer-safe test light, or a digital multi meter and test your brake light wiring. If you always have a ground signal, and only get a positive signal when you press the brake pedal, then you have positive switching brake lights. If you always have the positive wire energized, but only get ground to complete the circle when the brake pedal is pressed, then you have ground-switched brakes.