Neutral Safety Switch – What It Does & How To Fix It if Faulty

Modern vehicles are equipped with all kinds of awesome features and functions that make them safer, more convenient, and more user-friendly than their forebears, such as lane keep assist and blind spot monitoring. While these are nice additions to any vehicle, a few less recent and less heralded additions are just as important – and none more so than neutral safety switches.

In a few words, these switches are nothing short of lifesavers! In this article, we take a closer look at the neutral safety switch – what it is, what it does, the part it plays in keeping you and your vehicle safe from a potential accident, as well as what you should do if yours is faulty.

What Are Neutral Safety Switches?

It’s a safety feature built into an automatic transmission that doesn’t allow the vehicle to start while in gear – reverse or drive.

The vehicle will only start if the transmission lever is placed in park or neutral, both of which will not allow it to move forward when it’s turned on.

Depending on the make and model of your vehicle, this switch will either be located on the side of the transmission, within the transmission case itself, or on the shifter linkage.

The starter motor and ignition system are usually wired through the neutral safety switch, which is actually disconnected when the gear lever is in any one of the driving gears. If it is, the switch disconnects the wiring to the ignition system, leaving the electric current open and disconnected.

This prevents electric current from flowing to the ignition, thus not allowing the vehicle to be turned on. 

How Does a Neutral Safety Switch Work? And What Could Happen if It’s Faulty?

In short, a neutral safety switch prevents a vehicle from starting in any gear other than neutral or park when you turn the ignition key and the engine starts up. 

When a vehicle is in gear – drive, reverse, or any of the other available options such as first, second, or low on some vehicles – it will move as soon as the engine is turned on.

A bad neutral safety switch will not prevent the vehicle from turning on should it accidentally be placed in one of its driving gears.

At the very least, your vehicle could catch you off guard by starting to roll as soon as you turn the key or push the starter button to get your car started.

At worst, it could move forward or backward, hitting another car or another person in a crowded parking lot. Children could even accidentally turn a vehicle on if they’re inside, playing or fiddling with controls.

All of these things only take a split second to happen, and if you know the NSS in your car is faulty, don’t wait to get it fixed!

How Do You Know When the NSS Is Starting To Become Faulty, Or Has Failed?

Because of the nature of an automatic transmission and how vehicles are designed, it can be difficult to recognize when the NSS is going bad.

With that being said, most faulty ones will exhibit at least one of these four signs, hinting that it needs to be checked as soon as possible.

Engine Won’t Start At All

The most obvious sign of car trouble is when your engine doesn’t start at all.

This could be a sign of potential issues beyond a failed neutral safety switch – such as a dead battery that needs replacing, bad alternator, bad starter, failed fuel pump, or other battery issues, but it’s still also the most obvious sign of a problem that needs to be addressed.

Often, you can rule out these other issues by observing the vehicle’s behavior when attempting to start it.

A broken starter will often cause a clicking noise when the engine tries to start. A dead battery will often cause lights to dim or flicker, and could cause the check engine light to illuminate. Additionally, the turning over of the engine could be labored and slow.

A failed fuel pump will often result in the engine repeatedly trying to start, but failing to do so.

Ruling these other issues out or attempting to start the vehicle with no response from the ignition system usually signifies a neutral safety switch failure. Power to the ignition system can’t flow through if the electric circuit remains open.

Engine Won’t Start When The Vehicle Is In Park, But Will When It Is In Neutral

Another fairly obvious way you can tell if the NSS is faulty is if your car won’t start when it’s in park, but will start when shifted into neutral.

Most vehicles today won’t allow the key to be removed if it’s in any gear except park. At the very least, your vehicle will warn you with chimes or gauge cluster warning lights that it isn’t in park. Because of that, it’s usually pretty difficult to start it when it isn’t in park.

Still, you can test this without even getting out of your vehicle, by shifting into neutral and trying to start it again, especially if you aren’t getting any response when you turn the key or push the button to start it.

Engine Won’t Start When The Vehicle Is In Neutral, But Will When It Is In Park

This symptom is harder to identify because the majority of vehicles have systems in place that require them to be put into park before being turned off.

Though the majority of vehicles will be in park when turned on, this isn’t the case for all of them.

To test this, simply place the vehicle in neutral and try to start it. If it doesn’t start, the NSS may be faulty.

Engine Will Start Regardless of What Gear You’re In

Another more difficult symptom you can look out for to diagnose a problem is when you can fully start your vehicle in any gear or shift lever position.

Actually turning the vehicle on when it is in gear will most likely be a mistake, which is why the NSS is there in the first place. You can test if it’s working by attempting to start your vehicle in one or all of its available gears.

This issue would arise because the switch is always completing the electric current to the ignition system. If the NSS isn’t able to disconnect the electric current to the starter and ignition, it will need to be replaced and poses a danger if it isn’t as soon as possible.

For more information on the NSS, what it does, how to check it and how to replace it if need be, here’s a useful video we thought we’d share with you.

How Can I Fix A Faulty NSS Myself?

If you know for a fact that yours is faulty, you should replace it right away. Waiting any longer will only put your safety at risk.

You can do this yourself fairly easily, especially if your vehicle’s switch location is on the side of the transmission.

This becomes more difficult if it’s located on the shifter linkage, and is even more difficult (or sometimes impossible) if it is located within the transmission housing itself.

You can find the neutral safety switch’s location in your vehicle by consulting your owner’s manual. Once you locate it, it isn’t too difficult to replace.

Assess The Situation

The ability to locate the neutral safety switch and ease of access will probably be the best indicator of whether or not you want to tackle this replacement yourself, or hire a professional to do it for you instead.

Your personal tool availability will also play a part in this as car jack stands, various wrenches, and other tools that aren’t always commonly owned may need to be used.

If you don’t have enough space to work in, don’t have a variety of tools at your disposal, or don’t work on your vehicle that much, it may be easier to just have a mechanic do the work for you.

A new neutral safety switch doesn’t cost that much – usually between $100 and $400 – and a mechanic will have all the necessary tools to do the job at their disposal.

Labor costs will also usually be reasonable, as the job doesn’t involve tearing apart any major components.

Prepare Your Vehicle and Your Tools

Firstly, you will need to disconnect the battery. Almost anything beyond changing the oil or checking fluids will necessitate this, as working with electrical systems can result in an injury or short to the electric system.

Be sure to have the vehicle on a level parking area with the parking brake on. Jack the vehicle up and place jack stands under the front of it so that you will be able to crawl or slide underneath.

If your vehicle has a floor shifter or column shifter, you may not need to jack it up in order to reach it. All of this depends on the make and model of your particular vehicle.

Once you’ve located the neutral safety switch, you see what needs to be removed in order to reach it and the types of bolts holding it in place, you can get the necessary wrenches and ratchets to remove the switch and replace it.

Replace The Neutral Safety Switch

Before you actually remove the switch, you will need to remove its wiring harness, much like the connector in a headlight bulb.

You can then unscrew it from its mounting position and replace it with the new one.

Sometimes, especially if the switch is mounted below the vehicle, you will have to apply some pressure to remove it or use a screwdriver to pry it off.

Finish the Job

Once the new switch is screwed into the mounting area, reconnect its harness, reconnect the battery, and test the new switch.

If you can start the vehicle in park and neutral but not in other gears, you have successfully installed the neutral safety switch. Congratulations!

If this isn’t the case, though, you weren’t successful in your attempts. You will have to go back and re-install the switch or troubleshoot for other issues.

Always keep in mind that it’s best to replace carpeting, housing covers, and any other removed equipment after completing the job. If you have to fix something or repeat any part of the process, it will be a pain to remove everything again should the switch need to be adjusted or remounted.

What Can I Expect If I Take My Vehicle to a Mechanic?

Taking your vehicle to the mechanic to replace your neutral safety switch will probably be much easier than if you were to do it yourself.

If you want to save some money, you can buy the switch yourself. Just make sure that you get the correct part for your specific vehicle as identified in your owner’s manual, or else it won’t work.

The job itself doesn’t usually take too long to complete, especially if it’s a certified mechanic working on it. Labor costs are fairly low, and you most likely won’t have to drop your vehicle off or wait for a few days to have everything completed.

In total, the whole process should cost anywhere between $200 and $500, with luxury and specialized vehicles costing a bit more. All of this depends on the complication associated with the switch’s location and the wiring system.

A Quick Note About Manual Transmission Vehicles

Not every vehicle has an automatic transmission. For those with manual transmissions, a similar device (a clutch safety switch) is used to disable them from starting unless the clutch pedal is depressed.

Repairs for this type of switch are tricky and best left to a trusted mechanic, especially if you’re unfamiliar with vehicle electronics, don’t have a good number of tools at your disposal, or usually just perform simple maintenance tasks such as oil changes and headlight bulb replacements.

Wrapping It Up

Though often overlooked, whether because people falsely assume it’s a minor issue or because of ignorance, the neutral safety switch does a great deal to protect you and your car from injury and damage.

If you notice any issues arise, don’t wait to find out what’s going on, do so as soon as possible. Even though your “check engine” light may illuminate, there’s also the chance it may not. So, don’t rely on only this – knowing how to recognize the signs of a failing neutral safety switch could literally save your life!

Replacing a faulty one yourself is possible – however, if you have any uncertainty about doing so or just don’t have the time to work on this yourself, consult a mechanic. This is especially true if you have a brand-new vehicle or a luxury one, as these are generally more complicated to deal with, and you certainly don’t want to ruin anything.

Regardless of your vehicle type, the NSS is there to protect you, so don’t take it for granted.

Now that you know what it is, why it’s important for you, and what you need to do in case it gets faulty, happy driving!