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Relay works with your tow bar wiring system to ensure that your towed vehicle's turn signal lights flash in tandem with your RV's lights.
Features:
The purpose of a brake light relay kit is to prevent your towed car's brake signal from overriding the turn signal that comes from your RV. When your towed vehicle is properly wired and connected to your RV, its indicator lights will illuminate as you engage the turn signals in your RV. However, if you have only a four-diode system in place, the turn signal will be overridden by your towed car's brake signal as soon as your supplemental braking system presses the towed car's brake pedal. As a result, drivers behind you know only that you're slowing down and not that you are turning.
Installing a brake light relay in your towed vehicle fixes this problem by ensuring that your car's brake signal does not override the RV's turn signal. Therefore, your towed car's lights will function in accordance with your RV at all times.
Is a Relay Required?
To determine if a brake light relay is needed to properly wire your vehicle to be towed, answer the following questions.
Are you using a supplemental braking system that depresses the brake pedal in your towed car?
No - You do not need a brake light relay.
Yes - You may need a brake light relay. Continue on to the next question.
Do the brake lights on your towed car illuminate while the engine is off?
No - You do not need a brake light relay.
Yes - You may need a brake light relay. Continue on to the next question.
Do your towed car's brake lights act as both the brake signals and the turn signals?
No - You may need a brake light relay. Continue on to the next question.
Yes - Your towed car has a combined lighting system. You will need a brake light relay to ensure proper activation of its signal lights.
Does your towed car have separate brake lights and turn signals?
No - Your towed car has a combined lighting system. You will need a brake light relay.
Yes - Your towed car has a separate lighting system. You may need a brake light relay. Continue on to the next question.
Are you wiring your vehicle with a six-diode kit or a TowDaddy custom wiring harness?
No - You will need a brake light relay to ensure proper activation of your towed car's signal lights.
Yes - You do not need a brake light relay.
Most towed cars require the normally open installation method. Ford and Lincoln models with neutral tow kits and most automobiles that have a push-button start function will require the normally closed installation.
Normally Open
The diagram and steps shown below demonstrate the installation for normally open applications. Be sure to follow the instructions included with your relay kit for a more detailed process.
Normally Closed
The diagram and steps shown below demonstrate the installation for normally closed applications. If you have a Ford or Lincoln that has a neutral tow kit or if your car has a push-button start feature that will not start the engine when the brake fuse is removed, then you need to perform a normally closed installation. Be sure to follow the instructions included with your relay kit for a more detailed process. Normally closed operations may require additional connectors and length of wire that are not included with this kit.
Average Customer Rating: 4.7 out of 5 stars (563 Customer Reviews)
Relay works with your tow bar wiring system to ensure that your towed vehicle's turn signal lights flash in tandem with your RV's lights.Evidently Roadmaster had made some slight alterations from the depiction, for the better. The fuse wiring was a spade end with two fuse holders built in. The holder closest to the spades was for the original circuit and the other for the new circuit. This was very handy. I had watched the installation video and thought it would be fairly easy; therefore I attached the terminals to the green, black, and white wires before even going to the CR-V.
I did however purchase different spade connectors as I thought I may want to remove the brake relay switch in the future for another vehicle should I trade. Also the yellow connector is quite large and the video showed bending the wire over itself so that it would hold on the smaller wires. This was a wise decision.
What was the problem was the wiring in my CR-V. The video showed similar size wiring from the brake switch. What I found was smaller wire, loomed very close to the brake switch. Evidently Honda had made some modifications. I believe the wire was 22 gauge and there was no real way the blue or yellow connectors would have worked. That said, after disconnecting from the switch, stripping the loom back to get some exposed wiring, cutting and using the 22-16 gauge connectors, drilling a hole for the ground screw, etc. the switch worked perfectly.
I did vary the fuse location from the 7.5 Amp #29 Occupant Detection System (ODS) to the 15 Amp #28 Washer as I figured it would less likely interfere with any operation.
Installing on 2020 Jeep Trailhawk :
Pic #0557 : Roadmaster Base Plate Kit , Demco Supplemental Braking System , Diode Wiring Kit , Demco Battery Charge Wire Kit
Pic # 0548 ,0551 , 0559 Had to adjust the bracket plate to line up with the upper bolt holes
Pic #6028 finished install , mounted the operating unit to the top fuse box cover using automotive Velcro . Air cylinder , controller and LED light installed . Aside from the base plate bracket not lining up with the upper bolt holes I would give it 4 stars . My son in law is a master at solving mechanical issues .
Clear instructions and an easy install. Worked great for keeping toad lights operating correctly with supplimental breaking system. Thanks for quick shipping!
Well, if you don’t know about etrailer and you are into Towing or camping. You are missing the boat. This is the go to place and they have experts to guide you through the process of making sure that you find the right parts. I have purchased many things through the years from each trailer and could not be more pleased.
Basically part of a homemade wiring harness for a '79 Super Beetle. Can't say enough about our specialist at eTrailer--Kelsey knew her parts!
Installed as directions said to and all things are working as they should be. Helpful installation guide and video from trailer
My E-trailer experience was outstanding! From the great selection guide to the delivery to the installation support. The installation videos were very helpful. I had two installation issues that were answered with a prompt phone call. One call was on a Saturday morning. I highly recommend E-trailer!
Don’t buy it. Just unplug the wiring harness from brake switch. Then plug back in when you stop towing and go to drive vehicle. This requires tapping into fuse box on vehicle. Fuse box on 2009 dodge 2500 is like Fort Knox. You’d have to drill a hole in box or get crazy and mess with wiring bundle going into box to actually route a wire into a spare fuse outlet. Not worth it. Just unplug the small harness from brake switch. Then the system doesn’t know the vehicle is plugged in and it acts like a trailer lighting system. This you won’t have any interference with small harness unplugged from brake switch. Just remember to plug it back in. Also if you unplug harness you will not be able to shift vehicle transfer case into neutral or back out of neutral. Has to be plugged in the do the transfer case switch. 2009 dodge 2500
2014 Honda CRV Brake switch relay. -Roadmaster 88400
Relay switch are really simple to install, but the location of the brake switch and the small wires made it really difficult.
But it works as it should
I really don't know. Due to health issues I sold the RV. Never used the tow bar. I'll try to sell it.
Self installed, and easy to do if you just follow the videos and read the instructions. Quality hardware and fully functional after a full year of use. Jeep JK
The proportional breaking never worked right and on our last trip the system kept cutting out until it quit working all together. I was in the southern US and had to drive back to Canada without the aid of the breaking system. i tried to check it out and fix it but was unable to get continuous power to the brake buddy.
This system worked perfectly from experience. They help from trailers e trailer agents was crucial for guiding me through the process.
The brake light relay kit has worked well for a full year now!
Simple installation, perfect compatibility with other braking components.
Would highly recommend this product!
Not required on a 2023 F-150 Platinum. E-trailer should have done better with their homework.
Quality product. Great service from Etr ailer.
Did not need for my 2020 jeep with air force one
Didn't use
I used this relay along with a separate switch to turn on Firestone air suspension compressor. Remember always use electric grease on connections. Thank you etrailer. God bless. Jesus saves.
Has blown a fuse in vehicle.
Jenny N.
2/15/2024
I reached out to the manufacturer who advised that it sounds like the stop light switch fuse is the one that was blown. The fix is to locate the fuse in the fuse box which would be listed in the vehicle's manual. According to the manual I located the fuse panel is on the left side of the instrument panel which is to the left of the steering wheel. A label is attached to the fuse panel cover to identify each fuse for ease of replacement. The fuse number is number 12 which takes a 15 Amp. I still recommend checking your own manual as a double check. You can replace the fuse and it would allow the kit to work. If this does not help, please let me know.
Exactly as described - all parts included to install the brake light relay.
needed for my truck AAA+++
Michael
1/28/2024
no issues which is what i wanted
VERY GOOD PRODUCT
Excellent, towed my Wrangler about 5000 miles last yr and everything went well, plan on towing another 5k this yr with my RV
I have successfully completed the installation of the following items that I purchased from etrailer:
> Nighthawk RM-676 tow bar
> RM-524458-5 base plate
> DEMCO Stay in play DM86VR
> RM-152 diode wiring kit
> RM-156-25 charge wire kit
> RM-88400 brake switch relay kit
I work slow but methodically. I had no issues other than the high degree of difficulty for a 68 y/o man working alone. This project exceeds the abilities of someone NOT mechanically inclined. There is also the need for some specialty tools. I found that feeding the wiring through the dash, firewall, and underbody was more difficult than installing the front baseplate. Overall, I am satisfied with the function of this installation. I am glad I did it myself rather than having it done.
Tow vehicle: 2021 Entegra Emblem 36U
Towed vehicle: 2018 Ford Fusion Platinum Energi
Jeffrey
11/19/2022
The performance of this tow bar and associated hardware has been outstanding! Service and warranty follow up service from Roadmaster has also been outstanding! I am very satisfied with my purchase.
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Richard
10/24/2018
Working great with no problems.