Towing Wiring for Your Vehicle & Trailer

Vehicle Wiring for Towing

Curt T-Connector vehicle wiring harness with 4-pole flat trailer connector.

CUSTOM-FIT VEHICLE WIRING

Pollak trailer wiring mounting bracket and installation hardware.

WIRING MOUNTING BRACKETS

BRAKE CONTROLLER

BRAKE CONTROLLER WIRING KITS

Pollak 7 pole to 4 way connector adapter.

WIRING PLUGS

Hopkins adapter 4-pole to 7-pole and 4-pole.

WIRING ADAPTERS

Trailer-Side Wiring Parts

Hopkins 7-Way molded trailer wire connector.

TRAILER-SIDE CONNECTORS

etrailer trailer wiring 7-Way upgrade kit w/ junction box and RV style connector.

JUNCTION BOXES FOR WIRING

TRAILER WIRE & CABLES

HEAT SHRINK & BUTT CONNECTORS

WIRE MANAGEMENT

Pollak 7-Way to RV Socket LED circuit tester.

WIRING TESTERS

Trailer Wiring Guides & Diagrams

"How to Wire a 7 Way Trailer Plug" article.

"How to Wire Trailer Lights with a 4 Way Plug" article.

"A Trailer Maintenance Checklist" guide.

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Your Go-To Guide for Trailer Wiring, Vehicle Harnesses, and Brake Controllers

Whether you're installing trailer wiring, upgrading to a 7-way connector, or adding a brake controller, etrailer has the electrical parts you need to tow safely. Find custom-fit vehicle wiring harnesses, trailer-side connectors, junction boxes, wire management tools, testers, and complete wiring kits. From 4-way to 7-way adapters, brake controller wiring, and vehicle-specific harnesses, our gear is tested and ready for your next haul.

With over 75 years of assisting our neighbors and customers, over 1 million photos and videos taken to make sure you’re getting exactly what you need, and over 35 thousand installations completed, we’ve got the product know-how and experience to help you make the right choices for the job at hand.

What’s the difference between a 4-way and a 7-way trailer connector?

A 4-way connector handles basic lighting functions: running lights, left and right turn signals, and brake lights. A 7-way connector includes these functions plus additional circuits for things like electric trailer brakes, reverse lights, and a 12-volt power supply.

How do I wire my trailer lights with a 4-way plug?

Typically, the wiring colors are: white for ground, brown for running lights, yellow for left turn and brake lights, and green for right turn and brake lights. However, it's essential to test each wire to confirm its function, as colors can vary.

How do I route the power wire for a trailer wiring harness?

You can route the power wire under the vehicle, through the vehicle's interior, or directly from the battery if it's located in the trunk. Ensure the wire is protected and avoid areas with excessive heat or moving parts.

If you need more information on properly routing the power wire for your trailer wiring harness, be sure to check out this FAQ, Routing the Power Wire for a Trailer Wiring Harness.

Do I need a brake controller to tow a trailer with electric brakes?

Yes, a brake controller is necessary to manage the trailer's electric brakes. It ensures the trailer brakes engage proportionally with your vehicle's brakes, enhancing safety during towing.

What’s the purpose of a brake controller installation kit like the ETBC7?

The ETBC7 kit provides the necessary components to upgrade from a 4-way to a 7-way connector, allowing you to install a brake controller and access additional circuits needed for towing trailers with electric brakes.

How do I maintain my trailer's electrical system?

Regularly inspect connectors for corrosion, ensure all wiring is secure and undamaged, and test lights before each trip. Using dielectric grease on connections can help prevent corrosion.