Trailer Brake Controller Install

[tedcapra]

I have a 2019 Thor Sprinter 24SK. it does not have a MB 7 pin wiring harness but it does have one installed by Thor. I have no information as to where the other ends are so i can install a trailer brake controller. while digging around i did find a blue wire loose laying in the battery box under the driver floorboard. the red wire that adjoins it has a 30AMP fuse and it runs to the 7 pin connector.

I feel confident that the blue wire activates my trailer brakes and goes to the blue wire on the brake controller. i will splice into the 30amp fuse red wire and run it to the black positive wire on the controller. the white wire will be grounded off the battery terminal and the black wire of the controller will go to the brake light switch under the dash.

i attached pics

any thoughts, anything i have missed??

[steve2777]

I had similar questions regarding the new Siesta 24ST I just purchased. Posters on the irv2 forum were told by MB that because the Sprinter uses some kind of proprietary module, do it yourself efforts would likely invalidate the MB warranty, and MB dealers were quoting as much as $2k to do it. I decided instead to get a Curt 51180 Echo brake controller ($229 from Amazon) that plugs into the coach's female plug, and the toad male plug plugs into it. Powered from the plug, and applies brakes when the coach decelerates, or when you apply them from a Bluetooth app on your phone while driving. I couldn't be happier.

[Craigrandyelmer]

Which wire on the brake switch do you connect to my switch has 4 wires on it?

[tedcapra]

I was unable to determine which wire to use so i added a second brake switch just to run the trailer brake. its not fancy but it works. see attached pic.

[Dicynd]

After doing some research and talking to installers I settled on a Tekonsha 90250 which is a little spendy at "around" $300 !! You mount the main control on the trailer and have a remote that plugs into to 12v outlet in the dash and is hand held. As long as you have 12v at the 7pin your good to go. I was SHOCKED when I read in the owners manual that if I were pulling anything over 1000# that the item being pulled ( in my case a 5 x 8 utility trailer that weighs 850# empty ) needed brakes !!! I am paying $450+ to have electric brakes installed on the trailer :--(( I am having to be real careful not to let my trailer get "tongue heavy" so that it cuts into my GRVW. Right now it looks like we may have to drive naked to keep below max allowed weight ( might even have to shave the cats to get the weight down ;--))

[tedcapra]

the trailer i pulled was a 6x12 enclosed TA i was just moving a couch so the weight was maybe 2K. the trailer pulled and i had no issues stopping, i did get a little side push on the freeway when semis passed. I would like to pull a TOAD 4 down and am looking at very small car like the Chevy Spark (about 2200 LBS) i have seen several people doing this.

[Ridin1]

Where do you connect the red wire on the controller to activate the brakes?

[Maxwedge]

I located a company called TrailerJacks.com They have a "Plug & Play" harness that installs under driver seat to existing harness that allows installing a brake controler for the Sprinter. They also sell brake controllers ( your choice $) that goes along with it.

[Hooligan2]

If you contact Thor, they will provide wiring diagrams, plumbing and construction layout. Look under "Owner Resource" --Register here:https://www.thormotorcoach.com/owner-resource/

7 pin wiring diagram.