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Roadmaster Automatic Battery Disconnect with Switch for Towed Vehicle w/ Supplemental Braking System

Roadmaster Automatic Battery Disconnect with Switch for Towed Vehicle w/ Supplemental Braking System

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Roadmaster Auto Battery Disconnect Accessories and Parts - RM-766
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Conveniently disconnect your battery so that your vehicle can be flat towed per manufacturer instructions. System with switch charges your towed car's battery during towing to prevent dead battery and maintain charge for accessories. 1-636-306-4830 to order Roadmaster accessories and parts part number RM-766 or order online at Free expert support on all Roadmaster products. Great prices and Fastest Shipping for Roadmaster Automatic Battery Disconnect with Switch for Towed Vehicle w/ Supplemental Braking System. Accessories and Parts reviews from real customers.
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  • Reviews (171)
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Roadmaster Accessories and Parts

  • Tow Bar Wiring
  • Auto Battery Disconnect
  • Roadmaster

Conveniently disconnect your battery so that your vehicle can be flat towed per manufacturer instructions. System with switch charges your towed car's battery during towing to prevent dead battery and maintain charge for accessories.


  • Lets you easily disconnect your battery so that your vehicle can be towed behind your RV
    • Can only be used on vehicle on which battery must be disconnected for towing
    • Includes switch for installing in the towed vehicle
    • Consult your owner's manual
  • Eliminates inconvenience and the potential danger of pulling your battery cable
  • Operates with switch
  • Includes a corrosion-resistant, marine-grade solenoid with 200-amp constant duty and 600-amp surge
  • Works with almost any 12V battery
  • Comes pre-assembled for easy installation


  • Disconnecting the battery, whether manually or with the Roadmaster automatic disconnect, will affect your vehicle's electronics. You will need to reset various electrical components in your vehicle following use of this product.
  • Not for use with diesel engine vehicles, due to the high compression ratio of diesels the engine can surge up to 10 times that of a gasoline engine at start up and can cause the solenoid to fail.
  • A charge line, (RM-156-25 - sold separately), is a good idea if you have a braking system that is using power from the towed vehicles battery while it is disconnected.

766 Road Master Automatic Battery Disconnect

Replaces 765

Item # RM-766

Installation Details RM-766 Installation instructions

This Product Fits The Following Vehicles

Customer Satisfaction Score:

Customer Reviews

Roadmaster Automatic Battery Disconnect with Switch for Towed Vehicle w/ Supplemental Braking System - RM-766

Average Customer Rating:  4.8 out of 5 stars   (171 Customer Reviews)

Conveniently disconnect your battery so that your vehicle can be flat towed per manufacturer instructions. System with switch charges your towed car's battery during towing to prevent dead battery and maintain charge for accessories.


This product works great for our 2018 Ford Explorer. It works perfectly for our application and allows us to easily disconnect the vehicle battery when we are preparing to tow the Explorer.


The battery disconnect installation instructions were clear and the installation went well in my 2018 Chevrolet Colorado ... in spite of the kit missing a few pieces like a second star washer for connecting the two battery cables and the second piece of protective tubing. I covered the exposed energized solenoid terminals with electrical tape to prevent an potential inadvertent short in the future when working under the hood. Works as designed so far.

I towed the Colorado from Maine to Arizona last winter and the battery disconnect worked well for the entire trip. It made preparing the truck for towing and driving very easy!
Mike - 07/01/2020


This unit DOES NOT work with a diesel motor. When I asked for a complete assembly, this should not have been sent.
I need to return this item.

I sincerely apologize if this was recommended to you for your diesel motor. I will have our customer service reach out.
-- Etrailer Expert Jenny N - 09/07/2022


I received the Roadmaster remote battery disconnect in a timely manner and had it installed in my 2016 Chevy Colorado by a local RV dealer. I used it for the first time this week and it worked like a charm. I didn't lose any of my preset radio stations or any other data that I know of. Pushing a button on the dash is a lot easier than disconnecting and reconnecting battery cables.

Still working just fine.
Robert M - 09/09/2017


The RM-766 is a solid piece of hardware and comes with absolutely everything required for the install, right down to the "Tow" and "Drive" stickers for the switch. I use it to disconnect the battery in my 2016 Ford Edge 3.5L AWD, to help make it flat towable behind my RV. It works great and I do not have to open the hood and mess with battery cables while travelling. I like it.

There have been absolutely zero problems with this switch so far. Works like a charm.
Herbert M - 07/13/2018


Very good braking system, battery switch, nice easy to use thanks John H


The service and support staff was knowledgeable and extremely attentive to my questions and concerns, they were quick to solve my problems. Top of my recommendation list.


Arrived on schedule today and installed today, In stallation videos for my vehicle were excellent


I have a 2014 Silverado that I wanted to tow with my RV. In order to tow GM calls for the battery to be disconnected. This was the only product that I fond that would do what I wanted. It is slightly over priced in my opinion but it does the job. I have attached it to my aftermarket air box and ran the switch under the hood release. This way I can use the remote to unlock the doors when I am ready to unhook.


Love the ease of battery disconnection with this product. The electronics in my 2021 Silverado seem to hate being without power though, and the remote keyless entry is a little finicky for a few cycles after power is restored, by that’s a Chevrolet issue.


Item as listed


The product was as advertised and the delivery was also as promised. The order staff was very helpful and knowledgeable about the product and which model to order. The tech support was also very helpful and seemed to know the product and exactly what steps to take for a successful installation.


LOVE IT!! Most of my other friends do not have the disconnect on their vehicles and have to deal with dead batteries and running their tow vehicle engines every couple of hours.


Didn't need it, returned it.


Quite a bit of work to get it installed into the Chevy Spark. But it does work nicely.


Pain in the rear to install but got it installed.


always great service!


making towing and keeping battery up, what could be better?


Easy install


Everything works amazing
Thanks to all
at etrailer


Works exactly as advertised. Shipping was fast and well packed. Recommend


missing on off button

I will have our Customer Service team reach out to you.
-- Etrailer Expert Jenny N - 06/03/2022


Easy to install and did what it was supposed to do


I gave each and every one of the items I purchased a 5star rating because they each have contributed greatly to my confidence and sense of security about full-time RVing in my Class C rv towing my little car behind. Each product has been well made and thought out and the service from etrailer has been great....from price to shipping and packaging. I couldn't be more pleased with everything. Job well done. Thank you.


Would not respond to a phone call or answer a simple question. No more business with etrailer for me.

Show More Reviews

See what our Experts say about this Roadmaster Accessories and Parts

  • Can Roadmaster Automatic Battery Disconnect be Used on Positive Terminal of 2014 Jeep Wrangler
    The Roadmaster Automatic Battery Disconnect # RM-766 referenced in your question can absolutely be installed on your 2014 Jeep Wrangler Unlimited but it does need to be installed on the positive battery terminal. As you mentioned, the manual for your Jeep recommends disconnecting the negative terminal when flat towing, which provides a bit of a contradiction with the instructions for the Roadmaster Battery Disconnect. This recommendation is present in a lot of vehicle owner's manuals...
    view full answer...
  • Can Roadmaster Battery Disconnect Kit # RM-766 Install on 2014 Jeep Wrangler Unlimited
    The Roadmaster Automatic Battery Disconnect with Switch for Towed Vehicle w/ Supplemental Braking System # RM-766 that you referenced is designed to replace the older RM-765 that you also mentioned. The # RM-766 will fit your 2014 Wrangler and work well but we do not have a way to replace just the solenoid of the 765 to be a 766.
    view full answer...
  • Will Adding the Roadmaster Automatic Battery Disconnect on 2018 Ford Focus Void Warranty?
    The Roadmaster Automatic Battery Disconnect with Switch for Towed Vehicle w/ Supplemental Braking System # RM-766 will not violate your vehicle warranty according to the Magnuson-Moss Warranty Act because no damage will be caused as a result of adding this part, but it does make it possible to flat tow your 2018 Ford Focus without disconnecting the battery. The idea is to cut the power supply to the vehicle components when the switch is flipped so it will protect your vehicle from draining...
    view full answer...
  • Is Brake Lite Relay Needed When Flat Towing Vehicle with Battery Disconnect
    If you disconnect the battery of your vehicle with the disconnect kit part # RM-766 you actually wouldn't need a brake lite relay. Reason being that when the battery is disconnected the vehicle wouldn't be able to power the stoplights.
    view full answer...
  • Length of the Battery Cables on the Roadmaster Automatic Battery Disconnect Part # RM-766
    The two heavy duty wires that are included with the Roadmaster Automatic Battery Disconnect with Switch part # RM-766 are both 2' long. If you need more length then you can always splice a new longer wire of a similar size onto the switch. I called my contact at Roadmaster to confirm this.
    view full answer...
  • Why Does the Battery Need to be Disconnected to Flat Tow a Ford Edge
    Generally speaking, when the owner's manual calls for the battery to be disconnected it is because certain features need to be disabled so they do not draw power from the battery and drain it. If you need to know exactly which feature(s) that is then you would need to contact your local dealer as I would not be able to say for certain what those feature(s) are. I also cannot recommend going against the owner's manual in any way which includes not disconnecting the battery. If you would...
    view full answer...
  • Should Roadmaster Automatic Battery Disconnect be Installed on Positive or Negative Side of Battery
    The Roadmaster Automatic Battery Disconnect, part # RM-766, does need to be installed on the positive side of the battery, even on vehicles that state to disconnect the negative cable. Roadmaster released a tech bulletin about this which is probably what you read. The reason is because if you use the disconnect on the negative side you'll lose your towed vehicle's main ground to the chassis. This means that all of the accessories that need to operate on the toad must be grounded through...
    view full answer...
  • Battery Disconnect Recommendation for 2015 Ford Edge V6 Titanium Flat Towed
    The # RM-766 is the correct part to disconnect the battery on your 2015 Ford Edge and I do recommend this part for an easy way to protect your vehicle without needing to move wires each time. This disconnect makes it as easy as a flip of the switch on your dash to make your vehicle drivable or towable. This also will put a maintenance charge on the battery too as you drive. Ford states to disconnect the negative side so that's what we recommend sticking with. You should verify this with...
    view full answer...
  • Installing Roadmaster Automatic Battery Disconnect with Switch RM-766 on 2018 GMC Sierra 1500
    According to Roadmaster, the reason GM says that the negative side of the battery must be disconnected is a standard shop procedure. If you use hand tools (wrench) and start by removing the clamp on the positive side of the battery, then you might accidentally touch the wrench to a grounded component (frame, engine block, etc) on the truck and create a short circuit. Sparks will fly and the battery could be damaged. However, with the Roadmaster battery disconnect system, there are no such...
    view full answer...
  • Why Does Battery of 2014 Ford Fiesta with Automatic Transmission Have to be Disconnected
    The automatic transmission of your 2014 Ford Fiesta shifts electronically which is why the battery has to be disconnected when flat towing as well as following all of the other procedures outlined in the manual. You will have transmission problems if you don't disconnect the battery. I found a few people online who flat towed without disconnecting the battery and they had to have the transmission rebuilt. The transmission basically dropped back into gear while they were flat towing which...
    view full answer...
  • Why is Disconnecting Battery on 2019 Chevy Colorado When Flat Towing Needed
    On page 317 of the owner's manual of a 2019 Chevy Colorado it states that failure to disconnect the negative battery cable can cause damage to the vehicle, and this is referring to the electronics of the truck which could potentially be damaged by not disconnecting the battery. The "negatives" of not disconnecting the battery are that the truck's electronic systems will be damaged, and the damage would not be covered by warranty if you did not follow the procedure outlined in the owner's...
    view full answer...
  • Flat Tow Restrictions and Specifications for 2019 Chevrolet Colorado Z71 4 Wheel Drive
    According to the online copy of your Owner's Manual (page 316-317), only 4WD vehicles with a two-speed transfer case that have a Neutral and a 4-Low setting can be towed four wheels down. Please refer to the prescribed "Dingy Towing" procedures outlined in your Owner's Manual. It also states that the negative battery cable must be disconnected and not touch the terminals. However, we recommend installing an Automatic Battery Disconnect with Switch # RM-766. The Automatic Battery Disconnect...
    view full answer...
  • Battery Disconnect for Flat Towing 2016 Ford Focus
    The battery terminal on your 2016 Ford Focus does need to be disconnected, but you are absolutely right that you can use the battery disconnect. The right one for your 2016 Focus is the Roadmaster Automatic Battery Disconnect with Switch # RM-766. I have added a link to the instructions as well as a link to a video of the disconnect being installed on a Focus for you to check out.
    view full answer...
  • Will the Roadmaster Automatic Battery Disconnect Fit a 2013 Honda Fit Sport
    Yes, the Roadmaster Automatic Battery Disconnect with Switch part # RM-766 will fit your 2013 Honda Fit Sport. The reason you do not see it listed as a fit is because the owner's manual does not specify that the battery needs to be disconnected while in tow. However, the battery disconnect has a very universal design and I see no reason as to why it wouldn't work for you. I have attached a sample install video.
    view full answer...
  • Roadmaster Automatic Battery Disconnect is Disconnecting Battery when Vehicle Turning Off Ignition
    I reached out to my contact at Roadmaster because I have not heard of this particular issue happening before with the Automatic Battery Disconnect # RM-766. He said it's possible that something is going on with the switch itself and there is an easy way to find this out for sure. There is a small 7.5 amp fuse at the end of the "Battery Post" cable, which is for the switch. With the unit running and on, remove this fuse to cut off power to the switch. Then start your vehicle and turn it...
    view full answer...
  • Does Battery of 2017 Ford Edge Get Disconnected When Flat Towed
    There isn't a way around having to have your vehicle unplugged when flat towing it to the extent that it would reset your radio settings etc. The charge line kits like the # RM-766 allow you to put a maintenance charge on the vehicle's battery while the vehicle is disconnected but there isn't a way to accomplish both.
    view full answer...
  • Recommended Battery Disconnect Switch for Two 6V Batteries Connected in Series
    It sounds like you are needing a battery disconnect like the Roadmaster Automatic Battery Disconnect with Switch # RM-766. This kit will allow you to disconnect the batteries with just a flip of a switch. I have attached the complete installation instructions that you can take a look at, along with an image that shows how the unit will be connected to the battery.
    view full answer...
    Image 1 for
  • Will Battery Disconnect RM-765 Work On 2014 Smart Car?
    Based on my research, it is required that you disconnect your battery during towing. The Automatic Battery Disconnect For Towed Vehicles, Item # RM-766, is what you need. Consult your owner's manual to confirm what you need to do for your Smart car. If you need anything else to flat tow your Smart car then let me know. Links to additional information attached.
    view full answer...
  • Best Place to Mount Automatic Battery Disconnect from RoadMaster Part RM-766
    The most common place that they are mounted is on the fender or on the firewall, depending on battery location. The heavy gauge wire leads for the battery are long enough to allow flexibility as far as mounting location. It is not an extremely complex operation, and the simpler the operation, the less problems. We have not heard of any problems with the units we sold so far.
    view full answer...
  • Does Installation of the Roadmater RM-765 Auto Battery Disconnect Charge the 2008 Honda CR-V Battery
    The Roadmaster Auto Battery Disconnect, item # RM-766, includes all of the parts needed for installation on your 2008 Honda CR-V, and supplies a trickle charge from the towing vehicle to the towed vehicle battery when properly installed. You will not need to remove the fuse for flat towing if the battery disconnect is installed on your vehicle.
    view full answer...
  • Disconnecting the Battery of 2016 Ford Edge For Towing Behind RV
    I'd recommend using a Roadmaster Automatic Battery Disconnect, part # RM-766. The disconnect would allow you to 'disconnect' the battery with a flip of a switch. When the battery is disconnected, the taillight circuit from the RV will maintain the battery in the towed vehicle (you'll need to leave the running lights in the RV on for this to happen). The owner's manual specifically states that the battery needs to be disconnected, I wouldn't recommend doing anything else other than physically...
    view full answer...
  • Will the Brake Buddy Battery Maintainer work with Battery Disconnect RM-766
    The Battery Disconnect part # RM-766 installs on the positive battery wire so that when activated all power is cut for the vehicle. See attached chart. What you would need to do is install the # RM-766 after the connection you have for your Brake Buddy so that it can still draw voltage when needed even if the # RM-766 is activated.
    view full answer...
    Image 1 for
  • Key Position for Flat Towing a 2014 Jeep Wrangler Sahara
    Different vehicles have different requirements and procedures for flat towing. In order for your 2014 Jeep Wrangler Sahara to be flat towed, and really any vehicle, the steering wheel has to be unlocked which requires a certain key position. An automatic battery disconnect, # RM-766, is not a requirement to flat tow your Jeep. But if using a supplemental braking system, required in most states by law, and if it requires 12 volt power, you could install a 12 volt outlet kit, # RM-9332....
    view full answer...
  • Recommended Battery Disconnect For 2015 Ford Edge Titanium
    I confirmed with Roadmaster that # RM-766 is the correct part to disconnect the battery on your 2015 Ford Edge Titanium and I do recommend this part for an easy way to protect your vehicle without needing to move wires each time. This disconnect makes it as easy as a flip of the switch on your dash to make your vehicle drivable or towable. I've attached an installation video of this product for your convenience.
    view full answer...

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