Neutral Safety Switches
A vehicle can be started only in park or neutral on an automatic transmission equipped car. The device that ensures this is the neutral safety switch. It is a switch that closes a circuit in the starter so that ignition can happen when the transmission is in park or neutral. When the vehicle is in any other gear the switch is open which breaks the circuit and does not allow ignition to happen, thus the engine will not start. It is usually an electrical switch that draws power from the battery so that the circuit will close and ignition is allowed. Repair or replacement of a neutral safety switch may require more hands than one person has as the ignition must be held in start position for the switch to be removed. In a front wheel drive vehicle, the switch is located on the top of the transmission. The gearshift cable may need to be removed as well.