What Is a Neutral Safety Switch?

What Is a Neutral Safety Switch?

Last Updated December 29, 2023 | Meghan Drummond

Neutral safety switches prevent you from starting your car in any gear other than neutral or park.

Neutral safety switches have been around since the 1950s, and have been installed on almost every production car with an automatic transmission since the 1980s. Most people don’t ever think about the neutral safety switch. Unfortunately, if one starts to fail it can cause many problems for your car.

Simple diagram showing a neutral safety switch

How Does a Neutral Safety Switch Work?

When you turn your key to start your engine (or push a button), the battery sends a current to your engine’s starter. This tells the starter to fire up your engine so you can get on the road. The neutral safety switch simply disrupts that current if your car is in any gear other than neutral or park.

This is only true for vehicles with an automatic transmission. Manual transmissions have a similar apparatus attached to the clutch pedal. The clutch neutral switch prevents a vehicle from starting unless the clutch pedal is pressed. This is a simpler design than the neutral safety switch for automatics, and it’s cheaper to replace.

What Makes a Neutral Safety Switch Go Bad?

Like most car parts, age is the number one issue for neutral safety switches. Corrosion, dirt, moisture, and heat can also negatively affect a neutral safety switch. Because the switch is either housed in your transmission case or in the linkage, it’s exposed to the elements.

Cleaning your undercarriage is one way to prevent your neutral safety switch from going bad too quickly. Unfortunately, no matter how clean you keep it, eventually it will go bad.

Signs a Neutral Safety Switch Is No Longer Working

The engine starts when you’re in neutral or park, but not both.

The neutral safety switch is designed to allow you to turn your car on in park or neutral. If you can only start your engine in either neutral or park then you most likely have a faulty neutral safety switch. This problem can be caused by starter or battery issues as well, so it may be time for a trip to the mechanic.

You can’t start your car at all or can start it in any gear.

Most of the time when you can’t start your car in the morning, it’s the battery. But sometimes it can be the starter or the neutral safety switch. The battery is the first thing you should check in this situation, but if it doesn’t start easily it may be time to replace the neutral safety switch.

Being able to start your car in any gear sounds like it wouldn’t be a big deal, but it can actually lead to a lot of accidents. Imagine accidentally starting in reverse!

You have to jiggle your shifter to start your car.

This is a sure sign that something has come loose that shouldn’t be. Jiggling can help temporarily patch the connection, but eventually it’s going to come loose again.

How Do You Fix a Neutral Safety Switch?

An uninstalled neutral safety switch

Because of the neutral safety switch’s location, it’s not always an easy part to replace. Most people simply opt to take their vehicle to a mechanic. In general, this is a good policy with problems that are electrical in nature. But there are some problem-solving steps anyone can do.

A bad starter or battery will exhibit many of the same symptoms as a bad neutral safety switch. Making sure you’ve correctly identified the problem is the first step to fixing it.

Apply your brakes and turn the ignition to start. Then move the shift selector through the different positions to see if the car is able to crank in any of them. If it works differently than expected, it’s most likely a neutral safety switch problem.

Another trick, or something you can do if your engine refuses to crank, is to try wiggling your shifter. If the neutral safety switch is misadjusted then it may need a little push to get into the right position.

Once you’ve determined that it’s the neutral safety switch, you can use your car’s manual to locate and replace it with a new neutral safety switch. Just remember to unplug the battery first! If you’re hesitant about doing your own electrical work, you can also take your vehicle to a trusted mechanic.

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