Have you ever wondered how to determine the wire color for your Harley’s tail light? Well, you’re not alone. Many Harley owners find themselves in a similar situation, especially when trying to troubleshoot or upgrade their tail light system.

Today we aim to provide a comprehensive guide on correctly identifying the color of your Harley’s tail light wires.

Importance of Correct Wiring

Ensuring that your Harley’s tail light is wired correctly is not just about functionality but also safety.

Incorrectly wired tail lights can lead to accidents due to miscommunication with other drivers on the road. Hence, understanding your Harley’s wiring system is paramount.

Understanding Harley’s Wiring System

Harley-Davidson, like most motorcycle manufacturers, uses color coding in its wiring system. Each color corresponds to a specific function, making it easier to understand and troubleshoot the wiring system.

Color Codes in Harley’s Wiring System

Though colors can vary slightly between models, there are some common color codes that Harley-Davidson motorcycles tend to follow.

Common Wire Colors and their Functions

Here are some common wire colors and their usual functions:

  • Black: Ground
  • Red: Brake light
  • Blue: Tail light

This is a generalized list and may not be accurate for all models. Always consult your owner’s manual for the correct color code.

Steps to Determine Harley Tail Light Wire Colors

Identifying the wire colors for your Harley’s tail light can be straightforward if you follow these steps:

Step 1: Consult the Owner’s Manual

Your Harley’s owner’s manual should contain a wiring diagram with color codes. This should be your first point of reference.

Step 2: Inspect the Existing Wiring

If you’re replacing the tail light or fixing an issue, examine the existing wiring. The color of the wires leading to the tail light can give you a clue about their function.

Step 3: Use a Multimeter

If you’re still unsure, use a multimeter to test the wires. This can help confirm which wire is for the tail light.

Common Issues and Troubleshooting

Like any electrical system, Harley’s tail light wiring can encounter issues. Here are some common problems and how to troubleshoot them:

Flickering Tail Lights

If your tail light is flickering, it could be a sign of a loose connection. Check the wiring for any loose connections and secure them properly.

Non-Functional Tail Lights

If your tail light isn’t working, it could be due to a blown fuse, a burned-out bulb, or faulty wiring. Check the fuse and bulb first, as these are the easiest to fix. If the problem persists, it could be a wiring issue.

Safety Precautions

Working with electrical systems can be dangerous. Always disconnect the battery before working on your Harley’s wiring.

Wear rubber gloves to prevent any accidental shocks, and make sure your surroundings are dry to avoid any electrical mishaps.


Determining the wire color for your Harley’s tail light doesn’t have to be a daunting task. With a basic understanding of Harley’s color-coded wiring system, a copy of your owner’s manual, and a multimeter, you can confidently navigate your bike’s wiring.

Remember, safety comes first, so always take the necessary precautions when working with the electrical systems of your bike. Happy riding!

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