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Electrical damage can occur to the towed vehicle if its headlights are turned on while still connected to the motorhome. The Park Light Diode from Roadmaster will stop any interaction between the two park light systems, preventing electrical feedback and electrical damage.
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Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Hello everybody, this is Jeff at etrailer.com. Today we're gonna take a look at this Roadmaster Single Park Light Diode. Now basically when you're flat towing your vehicle electrical damage can occur to the tow vehicle, if it's headlights are turned on while you're still connected to the motor home. So this park light diode here from Roadmaster will stop any interaction between the two park light systems preventing electrical feedback and electrical damage. Now they do recommend installing this diode directly behind the electrical socket on the front of your vehicle. However, it can be installed anywhere in line before the connection to the towed vehicle's wiring.
This does have nice aluminum heat sink which prevents overheating. On the back, you can see it has a nice self stick adhesive pad for secure mounting. Maximum load is 85 amps at 12 volts per diode and this part is for a quantity of one diode. But that should do it for the review on the Roadmaster Single Park Light Diode..
Just what we needed at a great price. Very fast shipping.
Thanks.
Great 'insurance' policy for any towed vehicle. It never fails... you get to your destination, you are tired, you jump in your towed vehicle and turn on the lights. Too late! The damage is done. If you haven't turned of the lights of your coach and your towed is hard wired to use it's own lighting as 'trailer' lighting, you NEED THIS DIODE. A breeze to install and a cheap failsafe .
I didn't quite use this for the intended purpose. I was having trouble with the hazard lights backfeeding the brake controller and pulsing the trailer brakes on my 1988 Chevy 1 ton pickup. Broke out the wiring diagrams and turns out on the squarbodies, that's how they wired the brake lights. Installed this diode after the brake light switch and brake controller but before the hazard switch. Solved the problem. The diode seems to be built well. The fact that it has blade terminals on it makes the installation easy. Very happy so far.
I have only received the diode and installed it, I have not pulled the trailer yet. Connection was quick and easy with suppled connectors.
Worked great! Used it with a 15amp slow breaker on my charge line for flat towing my wt Maverick.
Worked perfectly to add the Right and Left front parking lights to lighting when car is being towed. I ended using the dual input version and will keep these for future use.
Very nice product. Completely sealed aluminum housing is high quality. It was just what I needed to prevent back feed on the battery charge wire between my towed jeep and motorhome.
Work great, perfect thank you.
My application is a little different. I had used a relay to feed battery voltage directly to the ignition coil on my 65 Corvair. The alternator warning light back fed from the battery causing the engine to keep running with the key off. I installed the diode in the line to the warning light. Problem solved. Great product. Easy to install and works as described.
Product is working great
Just what I needed. Thanks for the speedy delivery.
Great part, makes everything work as it should.
Works as advertised
Used this in conjunction with a 12V charge line from my Class A motorhome to the battery in my Jeep to provide charge to battery when towing and using BrakeBuddy. Prevents backflow discharge when stopped. Also put in fuse at front of coach and fuse at Jeep battery as protection for 12V system in case of chaffed wire or grounding.
Greg S.
10/9/2018
Towed that Jeep to several places last year. Still works just like its supposed to.
I bought 3 diodes for my 09 Saturn that was back feeding to my RV. This took care of the problem. Easy is it to install and peace of mind that I won't have a problem now . Had I known I didn't hade diodes on my wiring harness I would install them at the same time .but buyer beware on buying other people's products not for E trailer .
Craigc
11/14/2016
Its been one year now and a diodes are still doing their job
Came on time and did the trick
Very fast and easy transition. My order was delivered quickly and on delivered on time. This is my first purchase from etrailer, and I plan to buy from them again.
The product will be used in the 12 volt output of a Motorhome trailer connector to feed a tow vehicle. The diode is rated at 85 amps which covers any need I might have. The construction of the diode is first rate.
Cbtraveler
12/19/2017
Product is still working fine without any problems
Just received today but worked as advertised! Thank you for the great customer service!
Works as described. I used it in the charge line from the motorhome to the towed vehicle battery (2012 CR-V, diode in from charge line, diode out to CR-V battery).
John F.
9/9/2020
It still works as intended with no problems.
The diode does exactly what I need it to, and for which it was engineered and built.
Product serves my application. Wanted to be sure that the break away emergency battery power on trailer brakes, when activated, would not back feed to my truck and damage factory brake controller.
Installed in 7 conductor cable between truck and trailer. Under test it works fine. Hope I never need it on the road. Recommend it for protection from back feed voltage. Could be used in any DC voltage system when the flow of current must be controlled or protected.
This product works exactly as desired. The packaging is excellent, and it did the trick. I'd definitely recommend it to prevent backfeeding.
I'm very happy with etrailer, their selection of products, pricing, and their information. They truly differentiate themselves with the value add, yet keep the cost competitive. Way to do business!
John O.
4/25/2018
One year later its still working as good as new! very happy with this product.
Didn't know I needed this to wire my 7 pin connector for trailer brakes. My neighbor told me I would need it so I ordered it. It works great. I suggest you mention it when someone orders a 7 pin wiring harness for a newer car.
Pretty basic item here, it prevents current from going back and forth. And it does just that! Worked perfect for my situation on the living quarters gooseneck horse trailer. I had installed a new battery breakaway system that charges the battery when the trailer is plugged in to the truck. However in my case, when the trailer wasn't plugged into the truck, I was getting current back through the wiring harness from the house batteries that was charging the breakaway battery. Not good as over a short time period it would have drained the house batteries. This little item prevents that from happening. Thanks Guys!
The road master diode worked perfect I used it as a battery isolater between my trailer winch battery and my trailer brake battery so when I would use the electric winch it doesn't drain my trailer brake battery with combination with a isolater switch so long u wire it correctly it works perfect.
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Jacob
6/7/2025
The diode has been installed on my truck for a year now. Still working great. Still very happy with it.