Installation of Brake Controller on 2017 Mazda CX-5

Updated 09/12/2024 | Published 06/19/2018

Products Featured in This Question

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

(3557)

$118.63

Hook Probe Circuit Tester

(70)

$12.41

Question:

I would like to add a brake controller to my CX-5. I see that you have a universal kit but the instructions say to connect the controller to the brake light switch. My switch has 4 wires which go to a microprocessor. Which wire connects to the input of the controller?

asked by: Jeff

Expert Reply:

To find the correct brake light switch wire on your 2017 Mazda CX-5 you will need to use a circuit tester such as # PTW2993 and find the wire that only shows power when the brake pedal is depressed; that will be the correct wire to hook up.

To install a brake controller like the best-selling Prodigy P3 # 90195 on your 2017 Mazda CX-5 you first need to install Wiring Harness # 118746 to get a 4-way connector and as you mentioned, you'll also need the Universal Installation Kit for Trailer Brake Controllers # ETBC7.

expert reply by: Kyle S

Bill T.

9/6/2020

Did anyone ever resolve which of the 4 wires was correct? I've got a green with constant power, then I have a Grey, black and sort of blue color. Thank you!!!!

Jon G.

9/9/2020

We haven't heard anything else on this issue but I can say the green with constant power that you found is to power the controller. Check the grey, black, and blue color wires to see which one shows power only when the brake pedal is pressed and that's the cold side of your stop light switch. Then you can either test for continuity using a multimeter for the ground wire or you can try applying 12V power to see which of the 2 remaining wires causes the pin in the 5 o'clock position on your vehicle 7-Way to show power. That will be your brake controller output wire.

Jon

9/12/2024

@JonG I found that I do not have a wire that is only live when the brakes are pressed. It was advised that I get a universal stop light switch, which I don't mind. It seems simpler than cutting into those wires under the dash anyway. Thanks for your help.

Jon G.

9/12/2024

@Jon In cases where the stop light circuit is really difficult to find, the Universal Stop Light Switch Kit # RM-751000 is a great solution!

Erin

9/10/2024

My # ETBC7 came with a cheap little tester, but I'm not sure how to use it to test the wires on my 2015 CX-5. There are a bunch of wires there. I've never used a tester like this. Do I clip the alligator clip to a ground and touch the end to the wires? Or do I need to disconnect the brake light switch? Sorry, I'm just not sure what I'm doing here. Everything else that's hooked up. The brake controller is all I need to do. Thank you.