Where is the neutral safety switch located? It's actually easy to find. The neutral safety switch prevents the engine from starting unless the transmission is in park or neutral. The switch is wired between the ignition switch and the starter. When the ignition switch is on, so is power to the switch, but when the vehicle is in a gear other than park or neutral, the switch creates an open circuit. When the ignition switch is in the start position, no power is transferred to the starter.
On vehicles with a conventional neutral safety switch, the neutral safety switch also acts as a back-up light switch. The neutral safety switch on late model vehicles remains the same as it has been for many years. This is for the majority of vehicles, but not all.
The switch, regardless of its form, needs to be in a location where it can contact the parking pawl or shift linkage. The most common is a flat black box located directly behind the gearshift lever on the transmission. If the vehicle is a front wheel drive, the switch can be seen on top of the transmission, under the shift rod. It will have a multi electrical connector attached to it. These units are usually slotted where they are secured and adjustable. If the vehicle is a rear wheel drive, the switch will be on the driver's side on the transmission under the shift lever. It is easy to see and quite obvious.
Here is where the variations come into play. Some domestic and foreign vehicles have a switch that is quite different in shape and characteristics, but still has the same function and still needs to be located near the shift linkage. If after looking the part up on line or at the parts store, it looks similar in size and shape to a cigarette lighter, the location will be different. If the vehicle is a rear wheel drive with a floor shift, the switch will most likely be located at the gear shifter. Most of these switches are a push button type. They are threaded into the transmission where they contact a part of the shift linkage. Some switches are a proximity type (hall effect type) switch where the position of the linkage close to the switch causes a spike in electrical power to complete the circuit.
The last type of neutral safety switch is the internal transmission type. This switch is actually inserted into the valve body of the transmission under the parking pawl. It really is not too difficult to change, just a lot more work involved.
If a quick inspection of the vehicle does not reveal a neutral safety switch in these above locations, then it would be a good idea to ask the auto parts store for the whereabouts of the switch. It makes it easier to determine whether to replace it yourself or send it out.