This circuit made from three 12V DPDT PCB (printed circuit board) relays turns your rear turn signals into additional brake lights while allowing them to still function as brake lights.

I soldered wire to the appropriate relay pins, put pieces of popsicle stick between them, wrapped them in electrical tape and then filled the tape with epoxy to hold them together and waterproof them. Finished product:

 

Alternate Method

I later realized that another way to accomplish this is to install a 5 pol to 4 pole trailer light converter into the circuit for the turn signals.

Connect the "TO CAR" right turn, left turn and ground wires to the bike's turn signal wires. (Blue/Black, Blue/Red and Brown wires.

Connect the "TO TRAILER" wires to the turn signals.

 

© 2022 Drake Smith - Please do not use or reproduce this elsewhere.  Feel free to link to it though.