Connecting tow line battery charger

[dsisemore1]

My tow battery charger failed. I purchased a new Roadmaster Battery Charge Line Kit for Towed Vehicles. It comes with a red wire to connect from the six pin connector to a circuit breaker installed on the tow vehicle and then connects to the battery on the car. My old system (different manufacturer)had the red wire (middle pin on connector provides power from motorhome to tow vehicle) and a black wire that was connected to the ground on the connector. I did not install the original so just curious - can I use the original red wire since it is already connected and if I can what should I do with the black wire? The other option would be to take out all the previous wiring and rerun the new red wire? Just seems like I could use the original red wire. Suggestions?
I have a Blue Ox 6 way trailer connection - I have checked and the following is accurate. Brown - tail lights, Green - right turn, Yellow left turn, Blue - Brake power, Red - battery hot lead and White - Ground - However I have a black wire connected to ground pin and goes to the old charging device

[Horsedoc]

I ran fused wires from the battery of the coach to the battery of the Jeep in order to operate the Brake Buddy. Lights, brake and turn signals are magnetic from a 4 wire plug on the coach.
Jeep Tech didn't think too much of getting into the wiring of the Wrangler. I believe there is a system that can be installed wiring through the real tail lights. I did not feel confident in doing that.

[dsisemore1]

Using Blue Ox 6 way connector - verified following: Brown - tail lights, Green - right turn, Yellow - left turn, Blue - braking power, Red - battery hot lead, White - ground - black wire from charging device also attached to ground

[wa8yxm]

Yes you can use the original RED wire. I would put the breaker in the line to protect against OH C**P! things.

The black ground wire.. USE it same as with the original.. Far too many RV two outlets are a bit..er.. anemic.. on the ground lead. (I had to upgrade my grounds)

[Grit_dog]

I can’t think of a single tow vehicle/motor home that comes with a 6 round plug. Haven’t even seen or used one in almost 30 years. And I’m around multiple different trucks and trailers regularly day in day out for the same 30 years.
OP may have a 6 pin connector, idk. But it’s far from standard if he does.
Regardless, it doesn’t matter.
OP, so a “battery charge line kit” is a small DC-DC charger I presume?
I don’t follow what you’re saying about reusing the red wire or not. If you’re hooking into the 12V hot lead on your TV trailer plug, then that seems like the the same/right spot to hook up the new thingamgiggy.
And the ground can be hooked either to the toad or the trailer connector from the road to the tv but the toad and tv must be grounded together too sometimes via the actual ball mount. Sometimes via the wiring, or both.
Doesn’t matter if 6 or 7 pin setup.
Note there are 2 different wiring color conventions for 7 pin trailer hookups. But you got good advice above to verify regardless of color or wire position what the function of each wire/pin is.

[CA_Traveler]

Suggest you look up standard 6 pin connectors and follow those guidelines. While there are guidelines you should verify the actual usage via pin positions. The 6 pin connector has a ground and 12V charge line (ideally but yours?, if yours is different then consider some rewire). Ideally these 2 wires should be larger gauge wires due to the long run from battery to battery and voltage drop for 12V charging can be significant. Smaller wire for the lights are usually adequate.

ie Don't assume anthing about wire color in a RV, test and verify. Some who want better charge rates run 2 larger wires like 10+ gauge battery to battery with adequate 2 wire connectors.