2014 Mazda 3 Trailer Wiring | etrailer Lowest Price Trailer Wiring Guarantee. Installation instructions and lifetime expert support on all purchases of 2014 Mazda 3 Trailer Wiring. Order online at etrailer or call 800-298-8924. 2014 Mazda 3 OE Wiring Harnesses & Stereo Adapters — Mazda 3 2014, Back-Up Camera Retention Harness by Axxess®. Use this harness to connect your OEM backup camera to an aftermarket radio. This product is made from high-grade materials to meet the strictest standards of high quality..