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Roadmaster Single Park Light Diode

Roadmaster Single Park Light Diode

Item # RM-690
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Shipping Weight: 0.12 lbs
Roadmaster Tow Bar Wiring - RM-690
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Roadmaster Accessories and Parts - RM-690

  • Tow Bar Wiring
  • Diodes
  • Roadmaster

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.

  • Maximum load is 85 amps at 12 volts per diode
  • Qty: (1) Diode

690 Roadmaster Single Park Light Diode

Video of Roadmaster Single Park Light Diode

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Roadmaster Single Park Light Diode Installation - 2012 Jeep Grand Cherokee

Today on our 2012 Jeep Grand Cherokee we're going to be showing you how to install the Roadmaster Single Park light Diode that's used on the charge wire. Part number is RM-690. If we've got 12 volt power at the 7 pull in the back of our motor home we can actually use that power to trickle charge the charging system that's in our vehicle. Now to connect to our Park Light Diode we need to run a 12 volt wire from our plug in here at the front of the vehicle on back to where we'll eventually mount the diode closer to our 12 volt power connection source. We just run it kind of through the front of it here just so you have enough to wire it up, and then we can follow along with whatever wiring that we've ran. Those base plates are going to have at minimum a break away switch. In this case we've got an air line and a couple other things.

We'll just go along with it. Now we can take the end of our 12 volt wire and we're going to run it right underneath the coolant back here, and pull our slack on through. Looks good, it's going to sit there nicely. Now right here just inside of the, kind of the fuse box here, there's going to be a flat surface. Now on that flat surface we're going to be mounting our diode into position. It will be pretty much just like that.

What we'll do is bring our wire up. Just go ahead and cut it where we plan on putting the diode. We're going to strip both ends of that back. Then the side that we've got connected to our 6 pull in the front that needs to go to the end. Just pull that female spade connector off there.

Put that down on our wire and crimp it in really well. The other side there we'll put the other spade connector on. This is going to go to the side that says out. Let's connect our wire from the front to the inside. You're going to use a little bit of rubbing alcohol to clean up the area we plan on mounting it to. Then we'll pull the cover off the double sided tape here, get it mounted right into position.

I'm going to pull that end back and wrap this up with some electrical tape just to help keep out any moisture, anything like that, and reconnect it. Do the same thing on the other side here. We're going to slide this on the side labeled out. We'll use a couple of zip ties to get our wire secured off just so it's not moving around on us or anything. We'll do one before we get to the diode and we'll do one after, right here. Now in this particular application it's pretty nice, because we're going to be able to just run that wire right underneath this hose, and then we'll actually be able to go right underneath the cover that's located right there. We can back off the large hex bolt. Trim our wire to the appropriate length and we can add on a ring terminal. This ring terminal is not going to be provided nor is the wire, so pick that up on our website if you plan on doing it in this fashion. That'll go right down over that stud 00:03:49. Put the hex bolt back on, put your hex nut back on. All right, that's all there is to it. Now we've got a trickle feed charge and we're heading down the road. With our charge wire working properly that's going to complete our installation of the Roadmaster Single Park Light Diode. Part number RM-690 on our 2012 Jeep Grand Cherokee.

Customer Reviews

Roadmaster Single Park Light Diode - RM-690

Average Customer Rating:  4.8 out of 5 stars   (83 Customer Reviews)


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.


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.

Towed that Jeep to several places last year. Still works just like its supposed to.
Greg S - 10/09/2018


Product is great. Shipping department let me down for the first time. I had to call and ask why I didn’t get the email that the part had shipped after 4 days. Part shipped the next day. Person said shipping department was backed up with orders. Don’t believe it. Someone messed up I’m sure.


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!


Works great

Diode is still working properly.
Kelly W - 05/21/2022


Does what it's supposed to do. My warning lights do not come on anymore. That being said, it should be included or recommended for the Tekonsha brake controller system. I guess all vehicles don't have that problem, but why take the chance. I have a 2017 Toyota Highlander Hybrid.


Product arrived and and worked as recommended. Thanks etrailer!


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 .

Its been one year now and a diodes are still doing their job
Craigc - 11/14/2016


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.

Product is still working fine without any problems
CBTraveler - 12/19/2017


Product works great to keep taillights from feeding to reverse lights and vice versa


This diode done extremely well for my application. Used it on my box trailer. Made it where when I go to back up the strobe lights com on with the back up lights and horn and the horn or the back up lights will come on when I use the switch for the strobes


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!

One year later its still working as good as new! very happy with this product.
John O - 04/25/2018


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).

It still works as intended with no problems.
John F - 09/09/2020


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.


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.


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.


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 .


This has worked great on my boat keeping my trolling battery charged while fish. It keeps it topped off.
Ronald - 02/06/2022


tape was dried up, would not stick.

I will have our customer service team reach out to you.
-- Etrailer Expert Jenny N - 12/06/2021


I got this to isolate my emergency brake disconnect battery from the main trailer battery. I would have preferred if the included wire crimps were the heat shrink type. Shipping took forever and was not trackable. Otherwise, this was a super easy product to install. Thank you etrailer for making it easy!


Fast free delivery, Installed very easily, works perfectly!
This product was installed to protect my roadmaster invisibrake system when using the Hopkins towed vehicle light kit on my 2015 Jeep Wrangler.


I have a Class A Rv and it has a hydraulic pump on the brake lite switch. I was getting a back feed from the running light back to the pump. I installed this diode and it stopped the back feed. Works great and fast shipping from Etrailer. Thank you Ashley E. for all your help. I couldn't figure out what would solve this problem.


Installed the diode in-line coming off my brake wire to my tail lights to my third brake light on my 1941 hot rod. It keeps the turn signals, and running lights from ''feeding into '' my third brake light bar in my back window. Very easy to install.
I ordered two just because they are so handy to have around the shop.


Diode itself seems fine. But the connectors were loose fitting and the sleeve that fits over the wire was either too thin or too soft. As a result, when crimped onto the wire, the wire was still loose and came out with a light tug. Replaced the connectors with better ones. Is now working fine.


I had been looked for a towed vehicle lighting solution for a while and ran across this item on the etrailer web site. This is an easy to use product that is also economical. Installation was exactly as the package described - simple. Etrailer alsways has great prices and fast service. I've used them for all of my trailer parts needs for 5 years and will continue to be a customer.

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Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee Michael H
Expert Research:
Michael H
Employee Jameson C
Expert Research:
Jameson C
Employee Jeffrey L
Expert Research:
Jeffrey L
Employee Andrew K
Video by:
Andrew K
Employee Jeff D
Installed by:
Jeff D
Employee Jacob T
Video Edited:
Jacob T
Employee Randy B
Test Fit:
Randy B
Employee Wilson B
Updated by:
Wilson B
Employee Hannah L
Updated by:
Hannah L

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