How to Use Brake Controller With 2021 Mazda CX-5 With Only 4-Way

Updated 05/19/2023 | Published 05/18/2023

Products Featured in This Question

Universal Wiring Adapter for Curt Trailer Brake Controllers

(458)

$14.95

Curt Spectrum Trailer Brake Controller - Dash Mounted Knob - Up to 4 Axles - Proportional

(420)

$269.95

Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires

(3451)

$118.65

Question:

I have a 2021 Mazda CX 5 Signature with a 4 pin connector that was installed by the dealership that it was purchased from. I am not the original owner but Mazda verified that by my VIN. When I connect the small trailer, every thing but the brakes work. Turn signals work and I know the brakes are on the same wires. From what I see in your QandA is that this is most likely a bad ground. How would I go about fixing this?

asked by: Jacob C

Expert Reply:

The issue with your 2021 Mazda CX-5 isn't the wiring or ground, it's that you only have a 4-way, which controls the lighting, but does not control electric trailer brakes. Electric trailer brakes won't work without a 7-way and a brake controller, so you'll need a few extra parts:

- Universal Installation Kit for Trailer Brake Controller # ETBC7

- Curt Spectrum Trailer Brake Controller # C51170

- Universal Wiring Adapter # C51515

The 7-way that comes with the # ETBC7, which also gives you the wiring, circuit breakers, and rest of the hardware needed for installation. The brake controller will then give you the ability to use your brakes, set the brake power, and even has a screen with full text making it one of the easiest brake controllers to use.