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A stuck or misaligned supplemental braking system can quietly cause real damage by keeping your brake pedal slightly pressed. The Roadmaster Stop Light Switch Kit solves that by triggering your RV’s brake-monitoring system only when the towed car’s pedal is actually being applied. You’ll know right away if something isn’t right, so you can avoid tire and brake wear before it becomes expensive.
Instead of guessing whether your braking system is working, this kit gives you clear confirmation through your RV’s monitor. It ties into the towed vehicle’s brake pedal—so you’re seeing true brake action, not just air-cylinder movement. That means better awareness and confidence every time you’re on the road.
The Stop Light Switch Kit wires directly into the towed car’s fuse box, giving it a steady 12-volt supply. That constant current keeps your monitoring system reliable, even in setups where the ignition has no dedicated “tow” position. You get consistent performance without fluctuating signals or false alerts.
Some vehicles don’t have an ignition setting that supports flat towing electronics. This kit makes that a non-issue by providing its own dedicated connection path for brake activation signals. It keeps your system functional and accurate no matter how your ignition is designed.
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.
Today we're going to be taking a look at Roadmaster's line of custom stoplight switch kits. You'll want to refer to our fit guide for the appropriate switch kit for your vehicle.Here on our motor home we have our indicator light that's connected to our stoplight switch. When this light illuminates, we know that our braking system that is installed is applying the brake pedal in our towed vehicle. And we're going to get this signal thanks to our stoplight switch. Here when I hit the brake in our motor home, the light's illuminated so I know that our braking system is working properly.This stoplight switch is going to provide you with an additional brake stop signal. This is important if you're flat towing a vehicle that doesn't have a brake signal when in tow mode.
Without a signal you'll have no way of monitoring whether or not your brake pedal is being depressed. You can use this stoplight switch to connect to the indicator that comes with your supplemental braking system so you can verify for sure that your brake pedal's being depressed when you hit the brakes in your motor home.In most instances it'll be well hidden or blend in with the rest of the wiring down below so you won't even notice it. Here you can barely even glimpse the switch itself. And the kit comes with everything you need to get it installed. This includes the switch, the wiring, the fuse and the custom bracket that's specifically made for it to mount right onto your vehicle.
The bracket's really what makes it custom for your vehicle. It allows the switch to mount seamlessly and easily adjusts to the contour of your brake pedal.A less common use is for a brake controller. If your vehicle doesn't have a compatible brake signal for your brake controller then you can install one of these and get that signal for your brake controller to easily hook up to your trailer.And that completes our look at Roadmaster's line of custom stoplight switch kits.
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.