Connect for Success: Vehicle Trailer Wiring 101
You purchased a new trailer – congrats! Now, on to the tricky part: connecting and wiring your trailer to your vehicle. As your local trailer and hitch experts, we always recommend having your trailer hooked up by a professional (come on down to Southside Hitch, and we’ll get you ready to go!).
However, we also encourage trailer and hitch owners to understand how to wire their trailers safely and effectively. It’s simply a part of being a responsible trailer owner. Plus, if an issue ever arises while you’re on the road, you’ll need to know the ins and outs of trailer wiring to get you back up and on the move.
While this is not a fully comprehensive guide to connecting your trailer to your vehicle, it does give you step-by-step instructions for setting up the standard trailer wiring system and provides safety practices.
Let’s get started!
Trailer Wiring Systems
First things first, let’s understand what trailer wiring is and the systems available to you. Trailer wiring connects the electrical harness that serves the numerous functions of towing a trailer, such as connecting the trailer’s brakes, lights and other driving components to your vehicle.
Not all trailer wiring systems are built in the same way. Some are simple and provide taillight converter kits, whereas others include more advanced technology, such as sway controlling, which is required for large loads. However, all trailer wiring systems should include a standard connector that matches your trailer’s connector.
The trailer wiring system that comes with the purchase of your trailer will likely not feature any added accessories but will include the standard requirements needed to safely tow a trailer.
What's Included?
Within a trailer wiring system, here are a couple of the parts you can expect to find:
- Trailer brake lights. These are critical to keep the drivers around you aware of when you’re slowing down or stopping altogether.
- Turn signals. Once again, this alerts the drivers around you to your driving plans. Turning with a trailer can require additional time and space, so it’s important to have this connection hooked up properly.
- Reverse lights. To signal you’re backing up, whether you unload your boat into a body of water or adjust your trailer while parking, it’s important to get these lights hooked up and maintained for everyone’s safety.
- Running lights. These lights provide visibility in low-light conditions, like fog or darkness, alerting surrounding drivers to where your trailer begins and ends.
- Accessories wiring. For things like power jacks, sway control, additional lighting, leveling and more, you’ll need your wire connected to an auxiliary power source.
Wiring Colors & Coding
Understanding the type of wiring your trailer has while also comprehending what the various colors mean, is critical to setting up your trailer for success.
The Most Common Combination
Most trailer wiring systems designed with the 4-way connection system come with the following combination of colors:
- Brown. These are used for taillights and side marker lights.
- White. This is the ground wire, connecting your trailer to your vehicle’s electrical circuit.
- Yellow. This wire connects your LEFT turn signal and LEFT brake light.
- Green. This wire connects your RIGHT turn signal and RIGHT brake light.
Less Common Colors
More advanced or accessories-based trailer wiring systems will feature more wires than those mentioned above. For 5-way connection systems, you’ll have the four colored wires above plus the addition of a blue wire for your reverse lights. For 6-way connections, you’ll have the same as 5-way plus the addition of a black wire for your 12-volt power system. Other configurations like the 7-way or 12-way trailer connections could include blue, black, red, orange, red or gray wires.
4-Way Configurations
As mentioned, a 4-way wiring system is one of the most common systems you’ll come across when wiring up your trailer. If you happen to have a different system, it’s best to follow the manufacturer’s guidelines and recommendations.
4-Way connectors can come in flat or round configurations. The flat style is common for smaller trailers, while the round style is used for larger industrial trailers. The configuration should come color-coded to make it easy to connect each wire to the appropriate plug.
Wiring Safety & Best Practices
When it comes time to wire up your trailer to your vehicle, it’s always recommended to follow the manufacturer’s instructions and safety guidelines. Here are a few of our top tips:
- Inspect for any visible damage, such as frayed wires or corrosion. While a new trailer shouldn’t have any damage, this is a critical step if you’ve purchased a used trailer, no matter its age or use.
- Ensure connectors are firmly pressed together. Many times, connecting issues come down to the connectors not being fully pressed together, so make sure they’re fully pressed into one another before hitting the road.
- Avoid pinching wires. Reduce damage and avoid hazardous errors by ensuring your wires are not pinched at the harness and that the harness is safely stowed away.
- Conduct a light function test. Before you get on the road, double-check that all your turn signals, brakes, underlighting and additional accessories are properly wired and working with a light functioning test.
- Replace damaged wires, connectors and light bulbs. Don’t wait to fix something when you notice it’s worn down or broken, as this can severely impact your own safety as well as the safety of all drivers on the road with you.
If you run into any issues when wiring your trailer, never hesitate to give us a call at Southside Hitch. Our team is more than happy to walk through any and all issues over the phone while also providing you with a comprehensive check-up when you bring your trailer in.