When it comes to towing with your 2018 GMC Sierra, having a reliable and safe trailer wiring system is a must. Without it, your trailer lights, brakes, and turn signals won’t work properly, putting you and other drivers on the road at risk.
In this article, we’ll provide you with a comprehensive guide to the 2018 GMC Sierra trailer wiring diagram. We’ll cover everything from the different types of trailer wiring connectors to how to install and test your system. So, without further ado, let’s get started!
Types of Trailer Wiring Connectors
Before we dive into the wiring diagram, it’s important to understand the different types of trailer wiring connectors that are available. The most common types include:
4-Way Flat Connector
The 4-way flat connector is the most basic and common type of connector found on trailers. It has four pins that connect to the trailer’s brake lights, turn signals, and tail lights. This type of connector is typically used for small trailers, such as utility trailers, and can handle a maximum of 20 amps per circuit.
5-Way Flat Connector
The 5-way flat connector is similar to the 4-way connector, but adds an additional pin for the trailer’s ground wire. This type of connector is also used for small trailers and can handle a maximum of 20 amps per circuit.
6-Way Round Connector
The 6-way round connector has six pins that connect to the trailer’s brake lights, turn signals, tail lights, and ground wire. This type of connector is typically used for larger trailers, such as boat trailers or horse trailers, and can handle up to 30 amps per circuit.
7-Way Blade Connector
The 7-way blade connector is the most common type of connector found on larger trailers and RVs. It has seven pins that connect to the trailer’s brake lights, turn signals, tail lights, ground wire, and electric brakes (if equipped). This type of connector can handle up to 40 amps per circuit.
Wiring Diagram for the 2018 GMC Sierra
The 2018 GMC Sierra comes with a factory-installed trailer wiring harness, which makes installing a trailer wiring system much easier. The wiring harness is located under the bed of the truck and is designed to plug into the truck’s electrical system.
To install a trailer wiring system on your 2018 GMC Sierra, you’ll need to follow these steps:
Step 1: Gather your tools
Before you begin, you’ll need the following tools:
- Wire strippers
- Wire crimpers
- Electrical tape
- A voltage tester
Step 2: Locate the wiring harness
The wiring harness is located under the bed of the truck, near the rear bumper. To access it, you’ll need to remove the bed liner and any other obstructions.
Step 3: Connect the wiring harness to the trailer
Once you’ve located the wiring harness, you’ll need to connect it to the trailer’s wiring system. This can be done using a trailer wiring adapter, which is designed to plug into the wiring harness and convert it to the appropriate trailer wiring connector.
Step 4: Test the trailer wiring system
After you’ve connected the wiring harness to the trailer, it’s important to test the system to ensure that everything is working properly. To do this, you’ll need to use a voltage tester to check the trailer’s brake lights, turn signals, and tail lights.
FAQ
Q: Can I install a trailer wiring system myself?
A: Yes, with the right tools and some basic knowledge of electrical wiring, you can install a trailer wiring system yourself.
Q: Do I need a separate braking system for my trailer?
A: If your trailer weighs more than 1,500 pounds, you’ll need a separate braking system. Check your state’s laws for specific requirements.
Q: What’s the maximum towing capacity of the 2018 GMC Sierra?
A: The maximum towing capacity varies depending on the engine, transmission, and other factors. Check your owner’s manual or consult with a GMC dealer for specific information.
Q: Can I use the same wiring harness for different types of trailers?
A: Yes, as long as the trailer wiring connector matches the wiring harness connector. However, you may need to use a trailer wiring adapter to convert the wiring system to the appropriate connector.
Conclusion
Having a reliable and safe trailer wiring system is crucial when towing with your 2018 GMC Sierra. By understanding the different types of trailer wiring connectors and following the wiring diagram, you can ensure that your trailer’s lights, brakes, and turn signals work properly. If you have any questions or concerns about your trailer wiring system, consult with a professional mechanic or GMC dealer.
