
Professional Installation
Convenient Service
Trailer Hitches
Bike Racks
Running Boards
Roof Rails
Mazda CX-9 (2016–2023) Flat-4 Wiring Installation

The CX-9 uses a factory trailer-wiring connector behind the passenger-side rear cargo trim. We remove the necessary cargo flooring, storage trays, scuff panel, tire jack, cargo loops, and trim for access; plug in and secure the vehicle-specific converter harness; route the 4-flat for protected interior storage; test every lighting circuit; and carefully reassemble the cargo area.
Installation Time: Up to 30 additional minutes
Ready to Get Your Vehicle Set Up?
Skip the shop. Skip the wait.
Get your vehicle ready for lake days, mountain weekends, and family adventures — with professional installation completed at your home.

1. Disconnecting Power and Clearing the Cargo Area
The negative battery terminal is disconnected before the rear hatch is opened and the passenger-side cargo flooring and storage trays are removed. This protects the vehicle's electrical system and creates organized access to the rear trim.

2. Opening the Passenger-Side Rear Trim
The rear scuff panel is released carefully, then the tire jack, cargo loops, and required trim fasteners are removed. The passenger-side panel is eased back without damaging its alignment or locking tabs.

3. Connecting the Vehicle-Specific Harness
The factory trailer-wiring connector is located behind the passenger-side rear access area. The vehicle-specific harness is plugged fully into the OEM connector and checked to confirm that its locking tabs are seated.

4. Securing the Converter and Wiring
The converter module is mounted on a protected flat surface behind the trim with the supplied attachment material. Loose wiring is secured with cable ties so it remains clear of cargo, trim fasteners, and moving components.

5. Routing, Testing, and Reassembly
The 4-flat lead is routed to the center of the cargo area for use and protected storage. Running lights, brake lights, both turn signals, and circuit operation are tested before the dust cover, battery connection, trim panels, cargo loops, tire jack, trays, and flooring are restored.