The deal: We just put a flat bed on an '03 Tacoma, and have a wiring issue. We don't want to use the stock tail light assembly, but rather a "normal" trailer light. We have identified which pins in the original wiring harness heat up the turn signals, brakes, running lights and backup lights, but I am confused (typically so...). The original tail light assembly has one bulb for turn signal, one for b/u, and one for brakes/RUNNING LTS (2 wires to this bulb). The "normal" trailer light has only three wires: one for b/u, on for brake/TURN SIGNAL, and one for running lights. The back-up and running lights are a slam dunk; cut wires, attach where appropriate. However, if I run the two original wires for brakes and turn signal to the yellow wire on the new trailer light, how is the trailer light going to "know" to fire the brake filament or the turn signal filament in the 1157 bulb? I never have understood how one wire running to a 2-filament bulb works; I just hook 'em up and drive off in blissful ignorance. Any guidance/links to enlightenment appreciated. john