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When you’re towing, it’s important to know what’s really happening with your brakes—not just that a system is trying to activate. This stop light switch kit wires directly into the towed car’s fuse box for a constant 12-volt current and triggers your RV’s brake-monitoring system whenever the brake pedal is actually pressed. That means you see what’s really going on with the pedal itself, not just the air cylinder or actuator, giving you a clear and accurate signal every time.
A misaligned supplemental braking system can keep pressure on the pedal even when you’re not braking. That can cause drag, tire wear, or even damage to the braking system. By letting you know whenever the pedal is being depressed, this kit helps you catch setup issues before they lead to costly repairs. It’s a small safeguard that can make a big difference in keeping everything working right.
Some vehicles don’t have a tow position in the ignition, which can make it tricky to monitor the brakes correctly. This kit solves that by giving you a direct signal from the pedal, so the system still works properly even when there’s no dedicated tow mode. It’s a simple, reliable way to make sure your supplemental braking system always communicates exactly when your towed car’s brakes are engaged.
Flat towing can be a much more convenient way to take your car RVing with you than using a trailer or a tow dolly. It'll save you storage space both at home and at the campsite, and it takes less time and hassle to hook up.
To flat tow your vehicle, there are 5 basic components you're going to need: a tow bar, a base plate kit, a safety cable set, tow bar wiring, and a flat tow braking system.
| For the RV | Between the RV and Towed Car | For the Towed Car |
|---|---|---|
| Hitch | Tow bar | Base plate |
| Wiring plug | Safety cables | Braking system |
| Wiring adapter cord | Wiring kit/diodes |
The custom-fit base plate installs on the frame of your toad so you can connect the car to your RV with a tow bar. Hook up safety cables between the vehicles to ensure that the toad does not separate from the motorhome if the tow bar becomes detached. Tow bar wiring syncs your vehicle's signal lights with your motorhome's tail lights, as required by law in most states. Finally, the flat tow braking system - also required in most states - activates the brakes in the toad when you hit the brakes in the RV, making for smoother, safer braking, and preventing wear on your motorhome.
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Hi, everyone. Steve here with etrailer.com. Today we're looking at this Roadmaster Stoplight Switch Kit. Now folks, this is a custom fit application, so be sure you're double checking the fit guide here at etrailer.com on our homepage where it says, "My vehicle information," enter things like year, make and model, bed lengths, cab lengths, whatever it's asking you to be sure you get the right parts the first time. Now, what this is gonna do, this stoplight switch kit, it's gonna activate the motor home brake monitoring system whenever that brake pedal in the towed car is applied. It's gonna ensure that the supplemental braking system is functioning correctly and it's gonna work great for any application that does not have a tow position in the ignition.
So this will wire directly into the car's fuse box for constant current. It is running on 12 volts and you've got the little fuse box tapper here an inline fuse, some butt connectors, couple of wires, color coded, and then obviously the stoplight switch and you've got the bracket here, the custom bracket. Well, that's gonna wrap it up for our quick look together. I'm Steven, thanks for watching.
Ratings & Reviews
Victoria H.
1/14/2025
That's quite impressive Fred, nice ride!
Fred
1/8/2026
Everything works just fine! Great product and support! Thanks E-t
Josh B.
1/8/2026
Alan
9/8/2026
Its been a year and to be honest, I never have to think about my tow setup. Its there, it works perfect like the day I got it. I cant recommend this any higher. Smooth towing without worrying about it.
Lazer S.
9/8/2026
Kate F.
12/17/2025
I wish you could mount it there Donald, but those stop-light-switch studs are only designed to hold the switch bracket. Adding the pulley bracket changes the spacing and alignment, which can make the brake lights stay on, not come on, or throw off the Invisibrake’s operation. The studs also aren’t meant to handle the side-load from the cable, so Roadmaster doesn’t recommend using them. For drilling stainless, the trick is a cobalt bit (M35 or M42), slow speed, steady pressure, and cutting oil so the metal doesn’t work-harden. Are you new to flat towing, or just getting a different vehicle set-up?
Michael R.
1/18/2024
Still working great
Mark S.
11/3/2025
Its a good choice because its easy in easy out. I have two jeeps that can flat tow, so i was covered for braking in either one
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Kate F.
4/23/2026
Thank you for the detailed review and for sticking with the install George. That is a tight space to work in, and we really appreciate you sharing both the challenges and your thought process along the way. You make some very valid points about the alignment sensitivity and adjustability of the switch. I agree, that kind of precision fit without an easy lateral adjustment can make the install more tedious than it should be. It does not make it right, and feedback like this is exactly what helps highlight areas for improvement. It is great to hear that it has been working reliably for you over a few thousand miles so far. Your habit of checking function during hookup is a solid practice and definitely the way to go with setups like this. I will be passing your feedback along to the manufacturer for review, especially your notes on the switch design and mounting adjustability. Also, thank you for including photos even with the tight space. They are very helpful for others tackling the same install.