Gmc Sierra Tail Light Wiring Diagram

If you’re looking for a GMC Sierra tail light wiring diagram, you’ve come to the right place. We’ve gathered all of the information you’ll need to know in order to get your truck’s tail lights up and running again. Whether you’re dealing with a broken bulb or a faulty wire, we can help you troubleshoot the problem and get your Sierra back on the road.

If you’re in need of a GMC Sierra tail light wiring diagram, look no further! This comprehensive guide will tell you everything you need to know about the tail light wiring system on your GMC Sierra. We’ll go over the basics of the tail light circuit, including what each wire does and how to test for proper operation.

We’ll also touch on some troubleshooting tips in case you run into any issues. By the end of this article, you should have a good understanding of how the tail light system works on your GMC Sierra.

What Color are Tail Light Wires?

Most carmakers use red for positive and black for negative on the tail light wires. However, it’s important to check your specific vehicle to be sure. You can usually find this information in the owner’s manual or a wiring diagram.

What are the 3 Wires to a Tail Light?

Assuming you are referring to a standard North American tail light, there are three wires. The black wire is the ground wire and is typically attached to the metal body of the vehicle. The white wire is the low beam power wire and the red wire is the high beam power wire.

Both of these wires connect to the headlight switch inside the vehicle.

What is the Blue Wire on a Tail Light?

If you’re ever wondering what that blue wire is on your tail light, it’s most likely the turn signal. The turn signal is the blue wire because in old cars, the brake and tail lights were both red. So, to distinguish between the two, the turn signal was made blue.

Which Tail Light Wire is Positive?

There are a few different ways to identify which wire is the positive tail light wire. One way is to use a circuit tester or multimeter to test for voltage. Another way is to use a headlight bulb as a reference point.

The positive terminal on the bulb will be the positive tail light wire. If you’re still having trouble identifying which wire is which, consult a diagram of your vehicle’s electrical system. Once you’ve located the positive tail light wire, connect it to the Positive ( + ) terminal on your taillight assembly.


The GMC Sierra is a full-size pickup truck that was introduced in 1998 as a replacement for the previous generation of GMC trucks. The Sierra is available in two-door, four-door, and crew-cab body styles with either rear-wheel drive or four-wheel drive. The standard engine is a 4.3L V6, but buyers can opt for a 5.3L V8 or 6.2L V8.

All models come with automatic transmission and traction control. Standard features on the GMC Sierra include power windows, locks, and mirrors; cruise control; and AM/FM stereo with CD player. Optional features include heated seats, navigation system, sunroof, and premium sound system.

For model years 2014 and 2015, the GMC Sierra comes with a new feature called LED daytime running lights (DRLs). These lights are designed to improve visibility during the day and help make the truck more visible to other drivers on the road. The LED DRLs are located in the lower portion of the headlights and turn on automatically when the ignition is turned on.

There is also an optional LED tail light wiring diagram available for these model years that includes instructions on how to wire the taillights so they function as DRLs as well.

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Robert is a lifelong enthusiast of all things automotive. He has been working with wiring diagrams and schematics since he was in high school, and continues to use them as the foundation for his knowledge today.

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