If a neutral safety switch fails on a Chevrolet, the vehicle may not start as usual, if at all. Without the protection of the neutral safety switch, vehicles have the ability to start while in a gear other than park or neutral.
Signs of a faulty neutral safety switch include a vehicle's failure to start when turning the key. It may also start when the vehicle is in an unusual gear, like drive or reverse instead of the standard park or neutral. If a vehicle only starts while the driver is wiggling the shifter, replacement of the neutral safety switch is necessary. A check engine light may also come on to alert the driver to a problem with the car, which a mechanic may need to diagnose.
While some models are designed to ensure that the vehicle does not start without a working neutral safety switch, the presence of moisture, debris or metal shavings may cause a short when turning the key. This short can provide enough power for the car to start.
Neutral safety switches are components of automatic transmissions that disable the vehicle's ability to start unless it is in park or neutral. Depending on the vehicle's model, the switch serves as a means to interrupt either the key and the starter relay or the starter relay and the starter. Neutral safety switches are designed with an internal circuit that remains open unless the vehicle is in neutral or park.