Roadmaster Smart Diode Kit for Variable Voltage LED Tail Lights
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2013 Mini Cooper
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2013 Mini Cooper
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Smart diodes are our favorite option for getting brake and turn signals on your towed car. They are really well-made and reliable, plus pretty easy to install. This kit is for variable voltage/multiplex LED tail lights.
Features:
Specs:
Notes:
A variable voltage tail light (also known as multiplex) uses the same wire for both the brake light and the tail light, sending a 12-volt signal to the brake light and a 9-volt signal to the tail light. This works fine when you're driving, but when you are flat towing, the RV will send a 12-volt signal to both the brake light and tail light, making them the same level of brightness and impossible to distinguish from each other. The drivers behind you won't be able to tell the difference between your tail lights and your brake lights, which is a huge safety issue.
These smart diodes solve that problem by simply converting the signal from the RV to the lower voltage needed for your car's tail lights. They install permanently, but don't worry; everything will work as normal when you're not flat towing.
This kit is designed to work with LED lights only, so if you have incandescent variable voltage lights, you'll need kit RO94FR (sold separately) instead.
If the engine is off and your car's brake lights illuminate when you press the brake pedal, you need to install a brake light relay (RM-88400 - sold separately) with this kit. Without a relay, your car's brake signal will override the turn signal sent by the RV when you are slowing down to make a turn, creating a potentially dangerous situation. Other drivers will see that you're slowing down, but not that you're making a turn. With a brake light relay, you can signal both and travel safely.
A combined lighting system, or 2-wire system, uses the same light bulb to signal both braking and turning. (In other words, the car signals a turn by flashing the brake light.)
A separate lighting system, or 3-wire system, has the brake signal and the turn signal light up independently of each other. Typically, the turn signal is amber.
If your motorhome has a separate lighting system, add a tail light wiring converter (RM-732 - sold separately) to keep your setup functioning properly.
To complete your flat tow setup, you will need either a 4-way or 6-way round electrical connector on the front of your vehicle and a power cable to plug into the RV. Pick up a Roadmaster kit (RM-164-7 or RM-146-7 - sold separately) if you're still missing these important components.
Alternate Instructions
Customer Satisfaction Score:
93% were satisfied with this product
7% of customers were not satisfied
Ratings & Reviews
Works perfectly. Great product and sup port
Ray B.
2/21/2025
Still operating as installed
Works great, easy to install. Thanks for a good product.
Easy install
I ordered this back in June but had not opened the package until today when a friend was here to assist me with installing it. Unfortunately, it was missing the Insta-dapt Adapter and the hose clamps. I am sure I can use regular hose clamps but definitely need Instadapt Adapter. Would you please send that to me
Jenny N.
9/20/2023
I definitely will have our Customer Service team reach out to you.
Great YouTube videos. Very helpful
Thanks
I have been working with etrailer for years and have always been pleased with their website and service.
Easy ordering and fast shipping
Had everything I needed
Nice kit you have great videos on installing. Works great. Road master has great products and ETrailer has great prices and service.
No hassle with installation. Just follow the instructions and all will work out.
Great kit, and quality, works great through my initial install and testing and look forward to long term functioning.
Works great, easy to hook up and away we wenr
Good kit and etrailer installation video was fantastic. Install went well and was happy to have a helper when dealing with removal/reassembly of body parts.
On complaint that is directed at Roadmaster. They need to use some more appropriate self-tapping screws for taillight area. Metal is thin and self-tapping screws included are large and course threaded. The provided screws would not tighten up properly. I ended up needing to substitute some screws from my parts bin to get a good connection.
Braking system worked great on my Jeep. We towed the vehicle on a 6000 mile journey this year. We were up and more importantly, down the Rocky Mountains and the braking system never failed us. Would definitely recommend.
The wiring kit had excellent directions & video which made the install a breeze. It would be even better if it lighted more of the tail lights and brake lights. Most likely it is because of my vehicle design. We did a 7700 mile trip with no issues and worked as expected. I would recommend this item.
A complicated setup for the newer 4-wire tail light systems made easy with the online video featuring the make/model that I was wiring. Thank you.
Joseph
5/11/2025
Everything was going great until the passenger side brake light wire ped down onto the tail pipe and melted through, shorting the light to ground and failed to operate. Eventually, the 20 amp fuse for the brake lights in the Jeep Cherokee Trailhawk blew and took out both brake lights. It took a while to figure out this problem and I wont bore you with the troubleshooting details. Just remember when installing the wiring, make sure the slack is well tied using tie wraps or similar keeping the wires from getting into trouble.
Great customer support.
Exactly as stated. Have not installed it yet. But it will be good.
No tail lights on Jeep but camper had l ights
All works perfectly thank you again. Ya'll are great help when I work on my Jeeps.
Promptly supplied what I needed. Great installation videos!
I installed this on my 2021 Jeep Cherokee and it has worked well.
I installed this in a 2021 Jeep JL that had LED lights. The previous owner had installed the old-style diodes and it caused all sorts of problems with lights and sensors. This was a straight forward installation that worked exactly as expected. The main challenge is identifying the correct taillight lead, which can vary from model to model. Highly recommended!
Very good video explaining how to install. However, the forked connectors that press onto the tabs of the diodes were too big. etrailer was willing to send me a new set of diodes but I feared that wouldn't solve the issue. I ended up squeezing the connectors with a pliers to close the gaps so they'd all fit tightly like they should. You do NOT want a loose electrical connections so be sure to verify before you button things up.
Info for this part was:
At etrailer we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time.
Jim B.
9/4/2023
No problems after one year. Would recommend for Jeep owners with factory LEDs.