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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 complete kit includes everything you need for multiplex LED tail lights.
Features:
Specs:
Notes:
"Don't be intimidated by diodes: if you can strip and crimp wire, this installation will be no problem."
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 RM26FR (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.
Customer Satisfaction Score:
95% were satisfied with this product
5% of customers were not satisfied
Ratings & Reviews
I ordered an in stock item on Thursday but did not receive it until 9 days later. Maybe I didn't order it correctly to receive it sooner. I don't think a picture will show the products on my vehicle. That is a great thing!
The reason I gave 1 star is because the adaptor cord would not keep a good connection for the charge line causing me to have a dead battery on my tow vehicle when I arrived at my destination. Everything else worked as it should.
Nick S.
9/8/2025
I am sorry to hear about the adapter cord not keeping a good connection. I recommend inspecting each of the prongs in the adapter cord as well as the plugs on the RV and vehicle. One of the prongs could be bent or damaged causing that cord to not hold a steady connection when towing. Let me know if you notice any damaged prongs and we can figure out how to get that resolved for you.
Wiring kit was ok by roll of wire was to short ! Had to go buy more wire !! I would think for $200 plus I would get enough wire !!!
Great product that works for our 2021 Lincoln Navigator
Working good so far. Hated to cut the car wire harness to put them diods in though
I have just unpacked the product. It appears all packs ok.
It’s too bad it cost me XX dollars more to return the original product as it was the wrong product and then paying more for this product and then shipping cost me XX US from UPS.
I was told by the dealer I had a LED tail light system. I was given the wrong information. There were bulbs behind the lenses. I ordered the diode kit for the incandescent bulbs. I was told 1-2 days and got confirmation the Diode would arrive Friday 2/21. The mechanic had it back on his rack from Monday 2/24. The diode would now not arrive until 9 pm 2/24. Now the diode is now supposed to arrive 2/25 (asI write this , still has not arrived. Maybe tomorrow? Why would you just not send it UPS or FedEx from Salt Lake City to the Washington, DC metro area? Here is the trip this part has taken....
Moving Through Network
In Transit to Next Facility, Arriving Late
February 25, 2025
In Transit to Next Facility
February 23, 2025, 7:29 am
Departed USPS Regional Facility
JERSEY CITY NJ DISTRIBUTION CENTER
February 23, 2025, 5:19 am
Arrived at USPS Regional Facility
WASHINGTON DC DISTRIBUTION CENTER
February 23, 2025, 3:41 am
Departed USPS Regional Facility
LINTHICUM HEIGHTS MD DISTRIBUTION CENTER
February 23, 2025, 2:35 am
Arrived at USPS Regional Facility
LINTHICUM HEIGHTS MD DISTRIBUTION CENTER
February 23, 2025, 2:25 am
In Transit to Next Facility
February 23, 2025, 1:50 am
Departed USPS Regional Facility
JERSEY CITY NJ DISTRIBUTION CENTER
February 22, 2025, 10:36 pm
Arrived at USPS Regional Facility
JERSEY CITY NJ DISTRIBUTION CENTER
February 21, 2025, 4:05 pm
In Transit to Next Facility
February 21, 2025, 10:11 am
In Transit to Next Facility
February 20, 2025, 7:25 am
In Transit to Next Facility
February 19, 2025, 6:14 pm
Departed USPS Regional Facility
SALT LAKE CITY UT DISTRIBUTION CENTER
February 19, 2025, 4:40 am
Departed USPS Regional Facility
SALT LAKE CITY UT DISTRIBUTION CENTER
February 19, 2025, 3:18 am
Arrived at USPS Regional Facility
SALT LAKE CITY UT DISTRIBUTION CENTER
February 19, 2025, 3:10 am
Arrived at USPS Regional Origin Facility
SALT LAKE CITY UT DISTRIBUTION CENTER
February 19, 2025, 12:11 am
Accepted at USPS Origin Facility
SALT LAKE CITY, UT 84116
February 18, 2025, 10:56 pm
Shipping Label Created, USPS Awaiting Item
SALT LAKE CITY, UT 84116
February 17, 2025, 5:53 pm
Yes, tomorrow will be 2/26. This small part left Salt Lake City on 2/17. Poor work.
Works well and east to install just time consuming for layout, placement and overall cleanliness for super SANO install. The timing of installing this and the DUO Plug in Play must be done simultaneously. Layout the DUO first for placement locations and wire runs then this lighting wire run from front connection to rear area, then start at the front and make the connections from front to rear in one pass. Worked perfectly first time. Install fuses last.
Glenn
1/29/2025
Excellent wiring system. Just make sure you have all your connections in place and set before sealing the back of the main plug as you will not get back in there again. The wiring coil line connecting the RV to the Jeep is very tight but has proven itself over thousands of miles. I can recommend it.
Jameson C.
1/29/2025
Easy install! Thanks!
I purchased this as part of a package which included; Hitch and wiring for my 2022 Equinox, Base plate, Tow Bar, brake System and connecting air hose, break away cables, LED tow lights with wiring harness, and a trickle charger to keep the Equinox battery from going dead while I was towing it behind my class A RV.
I had etrailer do the install of all the components on my car and RV. All the workmanship was excellent and done in the amount of time they said it would take. Also because they did not have a video of this equipment being put on this year and model vehicle, I gave them permission to make a video(which added a extra day and a half to the install)and the installation was free. Everything has worked perfectly and I couldn't be happier. Etrailer is my go to for anything towing and also RV parts.
Jay
1/7/2025
What can I say other then it works every time and it is easy to hook and unhook
Works great
Make sure you route directly as there isn’t much extra length. Great product.
Easy to install and works as it should on my Bronco. I wish I would have continued reading the instructions regarding both ground wires "confusing" the SMART diode during installation. Lights would not work on the Bronco when connected to the motorhome. Did some troubleshooting and all connections were good. I pulled out the instruction sheet and read further, I removed one ground wire from one SMART diode and now it works perfectly.
Arrived a week early. Haven't installed yet.
Sold me the wrong kit. Yes my 2026 Tahoe has led lights but roadmaster rep actually warned me this kit does not work for me. I had used some wire out of the kit and asked if i could return the diodes since they didn’t fit my application. Etrailer yep said no problem but later emailed me i was stuck with them even though they told me it was correct kit.
Very easy to do worst part is fishing the wires and taking apart the rubber and plastic body molding
Do you have a question about this Flat Tow Wiring Harnes?
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Jim
2/28/2026
Still going strong. No problems at all. A very dependable air brake system.