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Roadmaster Brake-Lite Relay Kit Installation - 2017 Ford F-150

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How to Install the Roadmaster Brake-Lite Relay Kit on a 2017 Ford F-150


Speaker 1: Today on our 2017 Ford F-150, we're going to be installing Roadmaster's brake light relay kit, part number RM-88400. Now if you're going to use a braking system when flat towing your F-150, you want to verify if you need a brake light relay, because when you hit the brakes in your RV, that braking system is going to apply the brakes in the vehicle. When it does, it may override your turn signal, just like we did there. Our turn signal is currently being supplied by the signal from our RV. The brake signal from the vehicle shouldn't override it. If the brake signal does override your turn signal, you won't be in compliance with state laws.

So you'll need to install a brake light relay to disable that overriding brake signal.As you can see with our brake light relay installed and our turn signal on, when I hit the brake, it's not overridden, and everything works properly. Now we're going to disconnect our brake pedal sensor connector. Push in on the white tag here, and pull outward to release it. You'll now need to strip back the sheathing to expose the wires underneath, so we can tap into them. We're then going to take our purple and white wire, because that's our brake signal wire.we're going to cut that wire, and tap into it for our relay.

Make sure you give yourself enough coming off of both ends, and then strip back both ends.Now we have our harness here from our brake light relay kit. We're going to be making some connections to that into the wiring of the car. We'll start with our red wire, by crimping on a blue butt connector. The other end of the connector, we'll be connecting to the brown wire that we ran inside. We're then going to connect our blue wire from our harness, along with the black wire that we had run in for our brake light signal.

It's going to go to our RV, to a butt connector.The other end of this butt connector is going to go to the connector side of the wire that we just cut. Now we'll connect another blue butt connector to our black wire from our harness. That will connect to the other end of the wire that we cut. You can remove that bolt with a 10mm socket. Now connect the ring terminal to your white wire.

You can pick up ring terminals here at etrailer.com. We're going to connect that back through the bolt that we just removed, to get our ground. We can now plug our brake light switch back in. Then plug your relay in. It will only plug in one way. You can tidy up your wires, and make sure everything works properly.Now we'll need to tap in our brown wire that we ran inside to the brown wire from our wiring diode kit here. This is what will allow the RV's tail lamp signal to disable the brake lamp signal in the vehicle. Now twist the brown wire that we ran inside in with one side of the brown wire that we just cut out here. We'll be connecting those with a yellow heat shrink butt connector. You can pick up some of these here at etrailer.com. Then connect the other end to the other end of the brown wire that you just cut. That completes our installation of Roadmaster's brake light relay kit on our 2017 Ford F-150.


Shane T.

6/9/2021

I am a little confused about the black wire that is run in for the brake light signal. I have a 7 pin on the motor home with a 7 to 6 pin connecting wire to the towed vehicle. I have a yellow, brown, green, wires (Hopkins) from the rear of the toad to the front of the vehicle and have a grounded white ground wire to one of the terminals. I have a another wire for a battery maintainer on one of the 6 pins (one o'clock position). Do not have a black wire. Also where do you run the wires through the firewall? Thanks

Etrailer Expert

Jon G.

6/9/2021

The first thing I'd check is the position of that charge line wire. From my experience the 12V power on the 6-Way connector is the center pin. As long as the functions line up though that's what matters. When it comes to the black wire for the Brake-Lite Kit, this is what helps keep your brake lights functioning normally when you are needing to use your turn signals and slow down.

Shane T.

6/10/2021

Thanks, what is the source of the black wire. I assume it is brake signal output according to the diagram, and is to be attached to the brake light wire from the vehicle brake light switch. Where do I run that wire from to attach it?
Etrailer Expert

Jon G.

6/10/2021

@ShaneT Yes, just like you said. The diagram shows the black wire as being an output for the brake light circuit. You will just be running a length of wire from the black wire on the relay back to the brake lights on your towed vehicle.

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