To see if this custom-fit item will work for you please tell us what vehicle you'll use it with.
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Diode kit allows you to use your vehicle's tail lights and wiring system while preventing feedback from your RV. Wires 2-wire and 3-wire systems to operate as a combined lighting systems. Connectors and Extension loop sold separately.
Features:
Specs:
Note: For applications that have separate lighting, this kit will cause your brake lights to function as both brake and turn signal lights. A wiring converter (118158 - sold separately) and 2 additional diodes will be needed if you want to retain separate turn and brake signals.
Separate vs. Combined Lighting Systems
Some automobiles operate on a 3-wire system, wherein the brake signal and the turn signals travel along different wires to illuminate different lights. (Typically, these vehicles have amber turn signals.) This is referred to as a "separate lighting system". When you hook up for flat towing using this kit, your towed car's lighting system will operate in a combined fashion regardless of whether it typically has combined or separate lighting. This means that the brake and turn signals sent by your RV to your towed car will be carried on a single wire. As a result, your car's brake lights will do the flashing for the turn signals. Your vehicle will still function as designed when not hooked up to your RV.
Do You Need a Brake Light Relay?
Because this kit wires your vehicle as a combined system, a brake light relay (RM-88400 - sold separately) may be required if you use a supplemental braking system with your towing setup. A supplemental braking system depresses the brake pedal in your towed car every time you apply the brakes in your RV. So, if your towed car's brake lights illuminate when the brake pedal is pressed and the engine is off - as is the case when towing - then you need to install a relay to ensure that the lights on your towed car always act in accordance with the signals sent by your RV via the wiring harness. Without a relay, the brake signal from your towed car will override the turn signal sent by your RV when you slow down to make turns, creating a potential hazard.
Customer Satisfaction Score:
93% were satisfied with this product
7% of customers were not satisfied
Ratings & Reviews
Steve C.
3/4/2020
Works Great, Totally Transparent During Towing or Normal Use
Ronald
7/22/2025
It works as advertised, etrailer always represents well.
Jenny N.
9/25/2023
The wiring kit does have a limited lifetime warranty and I wanted to ask if you have reached out to Roadmaster?
Mike L.
6/17/2026
I'm sorry we dropped the ball like that, Lawrence! Let me look into that for you....
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Jeffrey
11/19/2022
I have no regrets with this purchase. Items preform as advertised with no issues. I am very satisfied with Roadmaster and Demco products.