Modulite style harness, but with separate brake/turn?

[Russ B]

Modulite makes a black box that allows one to run a standard 4-pin trailer harness off the tow vehicle's battery, rather than powering it directly from the tow vehicle's light wiring. As noted on the website, this is nice for cars (like mine) that monitor their own tail-lights and get upset when you put additional load on the tail-light wiring. The Modulite black box also combines the brake light and turn signal functions to match the standard trailer practice of a common bulb.

My question is: has anyone seen something similar that would retain the separate brake and turn-signals, but still provide the function of taking power from the tow vehicle's battery? I am thinking about using a taillight assembly sourced from a car that has separate turn signal and brake lights (and tails, for that matter).

I guess the DIY route would be an array of relays in the tow vehicle feeding power to a 6-pin trailer plug.

[I guess this could go in Electrical Secrets, too. Move as you see fit.]

[del]

My question is: has anyone seen something similar that would retain the separate brake and turn-signals, but still provide the function of taking power from the tow vehicle's battery? I am thinking about using a taillight assembly sourced from a car that has separate turn signal and brake lights (and tails, for that matter).

I guess the DIY route would be an array of relays in the tow vehicle feeding power to a 6-pin trailer plug.

Doing this would be a simple (if you find wiring simple) wiring exercise. You need four relays (right, left, brake, and tail).
The reason I did not go this rought is you now have a unique wiring for your car and trailer. You can not pull any other trailer with this wiring, and no one else can pull your trailer.

del

[Russ B]

Thanks for the reply.

Yeah, the unique wiring would be a bummer for lending the trailer out to friends and family. Maybe I could consider it a security feature? Ha.

[brian_bp]

I would expect these to be easy to find... typically identified as "5 wire" modules, versus the "4 wire" style with combined brake and turn. Now that I've said that, I can't find any in a quick web search!

For the compatibility issue...
It would be possible to install both modules, each feeding its own connector. Lots of vehicles have both a four-pole inline and a 7-pole RV style connector; this just takes that one step further to separate isolation modules.

I have considered doing this for my current travel trailer, feeding separate turn signals to the 7-way (and upgrading my trailer to use them) while continuing to feed the OEM 4-way with the OEM wiring adapter (for the utility trailer).