Trailer Brake Wiring Harness | etrailer Replace the damaged 7-way, RV-style trailer connector on your vehicle with this T-One harnessLite reduces strain on wiring system.Brake controller adapter plugs in beneath your dash and lets of Tekonsha Brake Controller Adapter This adapter plugs into the 4-pin connector on your vehicle's built-in brake control wiring harness harness is located near the steering column, Amazon: trailer brake wiring harness Amazon's Choice for trailer brake wiring harness. Tekonsha 3015-P Brake Control Wiring Adapter for GM. 4.6 out of 5 stars 384. $9 $ 9. 80 $16 $ 16. 20. Get it as soon as Tue, Apr 16. FREE Shipping on orders over $25 shipped by Amazon.