There may be many reasons why you may want to wire a two-way toggle switch into your car. A two-way toggle switch is often used to switch power between two devices on one switch. For whatever reason the toggle switch is needed, the installation may seem like a daunting task for those who are unfamiliar with working on electrical circuits. Luckily, wiring a two-way toggle switch is a relatively simple task.
Disconnect the battery. Do not attempt to work with your car's electrical circuits with the power on, as this could result in damage to electrical equipment.
Identify the terminals on the toggle switch. The middle terminal is the common terminal. If you are using the switch for lighting or other power control, the common terminal connects to the power source. If you are using the switch for audio purposes, this would be the input. The left and right terminals, sometimes labelled "A" and "B," are the output connections.
Attach the power wire to the common terminal of the switch. Use a soldering iron to solder the connection, or other method depending on how the toggle switch is made.
Attach one of the output wires to the left terminal. This wire will receive power when the switch is in the left position. Attach the second wire to the right terminal. This wire will receive power when the switch is in the right position.
Reconnect the battery and power on the circuit. Switch between both positions to make sure that the switch is wired and working properly.
Mount the switch. Use the mounting bracket that came with your toggle switch, if applicable. Be sure to mount the switch so as to avoid accidental shock. If the switch is left unmounted, use electrical tape to cover the terminals.