Captain Skip

I've finally got my JK all set up to tow behind my motorhome. I installed a Hopkins HM56200 plug and play wiring harness and a Hopkins brake light relay kit. The relay kit isolates the brake lights so that when the brake pedal is depressed when the Jeep is off, the signal lights will still function and not be overridden by the Jeep brake lights. (I'm using a NSA ReadyBrute Elite II tow bar with surge brake)
I added a flasher unit to my 3rd brake light that makes the 3rd light flash a couple times before staying on steady when the brakes are applied. Works perfectly when the Jeep is running. The other brake lights, tail lights and signal lights all work properly when the Jeep is shut off and being towed. The problem is the 3rd brake light will not work when under tow as the Hopkins harness does not connect to it.
The tow bar came with a small LED that I mounted on the dash of the motorhome and attached upstream of the brake relay so that when the brakes are applied on the Jeep while being towed, the LED will light up. This lets me know if the brakes are still on before I try towing the Jeep. Works perfectly.
I was thinking about splicing into the line for the dash LED and running a wire back to the 3rd brake light so when the brakes are applied the LED on the motorhome dash will light up as well as the 3rd brake light. But, when I'm unhooked and running the Jeep the 3rd brake light functions through the Jeeps wiring system.
My concern is when I'm running the Jeep if I put the jumper from the LED brake line to the 3rd brake light that I'll have power coming in to the 3rd brake light from two sources - the Jeep wiring and the jumper. Will having the two wires both providing power put 24 volts instead of 12 volts into the 3rd brake light? Or, am I better off to deadhead the power from the Jeep's harness to the 3rd brake light and just use the jumper all the time? I got the flasher unit to protect my azz when towing the Jeep to make sure people behind me see that I'm stopping and I really want it to work while towing.
Thanks

Seizer

Do have your wiring diagram handy to post up showing this flasher unit? If I understand correctly the towing harness from the motor home that connects to your Jeep, currently does not have an output for the flasher?

Captain Skip

This is the schematic for the brake relay. I'm thinking of splicing inline with the line that powers the LED on the motorhome dash and running it directly to the 3rd brake light.

Seizer

Hmm instead of running wire from that LED indicator, why not just make a jumper from your working lower brake lights so that it turns on the 3rd flashing light. If you did as you say with the LED indicator and add a new wire to the 3rd brake light, how could it get 24V if you have the Jeep disconnected from the motor home? They’d have to be wired in series to create that voltage.

See if you can get @ronjenx thoughts. He’s very savvy electrically.

resharp001

I presume that this is just something you want, more than something you feel is really necessary. I get that if you're just trying to do it for the novelty. Otherwise, it seems like a lot of effort for nothing IMO. I've towed my jeep around behind a motorhome for years and several thousands of miles. I never worried about a 3rd brake light back there at all. In fact, until this year I didn't even have a 3rd brake light on my jeep. I was never concerned about someone seeing either big ole motorhome tail/signal lights nor the taillights on the jeep flashing. I realize that commentary didn't help you at all sorry.

Captain Skip

I hear you, it’s OK. I tend to overdo everything. If something requires 2 nails I put in 4 screws!

resharp001

stay safe out there and enjoy your travels!