Unlike a manual transmission, an automatic transmission cannot be started in gear thanks to the neutral safety switch. If this part fails, you may be able to start your car or truck while in gear; causing it to lurch immediately. Obviously, this can pose many safety hazards when parked on hills. It could also result in property damage if you are parked close to another car or structure. This, however, may be an indication that the switch just needs an adjustment rather than a complete replacement. The most likely symptom that the neutral safety switch has failed is not being able to start the car at all, even if it is in PARK or NEUTRAL. You won't even hear a click sound coming from the starter solenoid because the switch will stay open and no current will get to the starter. If you turn your ignition to the ON position, press on the brake, and go through the gears a couple of times, you can then try to start the car again. Even if you are successful, it is time to get that switch replaced.
Neutral safety switches (or transmission range selectors/switches) were invented in the 1990s as a way to help the transmission control module process calculations and shift selections based on the gear that the transmission was in. It also serves the purpose of preventing certain functions while in PARK, NEUTRAL, or other drive gears. They are installed in the shifter assembly or close to where the shifter meets the transmission. If your shifter is on the steering column, then it will likely be somewhere in the column. Since they are a safety device, replacing the neutral safety switch when it goes (or is going) bad is imperative.
In order to do so, you first have to access it. That is different on every vehicle, but once you have done so you can start by disconnecting the wire harness connector. Be advised, all repairs done to electrical components require you to disconnect the battery first. Once the wire harness connector has been unplugged, you can unbolt it from the mounting flange. It will likely have some sort of shaft or rod that is integrated with the shifter assembly. You may have to remove some pins or clips to free it. Now, replace the old part with a new one. Lastly, finish up by re-installing all the other components you removed to access the neutral safety switch. Reconnect the battery, and attempt to start the car.
Finding the right parts for you car doesn't have to stress you out. In fact, we at Car Parts Discount have made it as easy as possible to find what you are looking for; be it a neutral safety switch, transmission range selector, or something else. Our parts are all made by top name brands you are familiar with and trust, so you can be sure that the parts you order and receive are going to work right the first time. If, in the off chance, something goes wrong, we are always available to exchange your parts under warranty. There's no need to put off fixing your car or truck any longer.