Wiring a 2-Way Switch - how-to-wire-it This should give you a good basic understanding how the 2-way switch circuit works and will help you in adding or changing a 2-way switch. So now that you have a basic concept of wiring a 2-way switch, let's look at the following 2-way switch diagrams to see which type of circuit scenario you have. Mack, Turn Signal Switch, Polycarbonate | Truck-Lite 900Y73. Mack, Turn Signal Switch, Polycarbonate Add to Wish List 7 wire harness. Pilot light for turn signal and hazard warning. 10 bulb capacity for hazard warning, 5 bulbs per side for turn signal flashing. Recommend flasher #263, not included.