American cars are wired to where the turn signal element is also the brake light element, same element two jobs. This is accomplished through the turn signal switch. Japanese vehicles use a different light element for each function, ie. right turn, left turn, brake, clearance. You can buy a trailer adapter to go between a Jap car and a trailer wired with 3 wires rt. turn(&brake), lft.turn(&brake) and clearance. These adapters cost from $20-$30 and are available at most any auto parts store. Just get a generic one and wire it in ahead of the back bumper.

88 Sam 4.16,welded rear,lock-rite frnt,31"Hi-tech muds on Ford truck wagon wheels, 4.5 spoa,5k quick mount Ramsey