Installation Instructions for Brake Buddy Select 3 Braking System

Updated 07/27/2026 | Published 12/11/2021

Question:

I dont have instruction manual for Brake Buddy on wiring to battery. Is there one I can download

asked by: Bill R

Helpful Expert Reply:

I am sorry to hear that you did not receive the instructions for your Brake Buddy Select 3 Portable Supplemental Braking System # HM39524. But yes, there is an online version of the instructions and I have linked them here for you.

The Brake Buddy Select 3 draws power directly from your towed car's battery. To do this, the included wiring harness connects to your car's battery. Install the harness by routing the wire end through your car's firewall and into your engine compartment. Connect the harness to your battery with the included battery wire and ring terminal. I have also include a couple of pictures from the instructions manual for you to quickly reference.

expert reply by: Scott S

Brake Buddy Diagram
(click to enlarge)

Brake Buddy Instructions
(click to enlarge)

Wayne N.

5/21/2026

Does etrailer stock all the wiring in this diagram to install a brake buddy select 3. I have the unit and the remote. I would need all the wires shown in your diagram under the hood and inside the tow vehicle. I do have the connector harness coming off the unit. If so, how much for all of it?

Jeff A.

7/27/2026

@WayneN They are out of business and zero sources for the wiring kit.

Claire H.

7/27/2026

@WayneN Jeff is correct, they have gone out of business, and we no longer have any parts for replacing the wiring harness for the Brake Buddy 3. A similar portable braking unit would be something like the Blue Ox Patriot or the Curt RVibrake 4.