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Toyota Prius Alarm Keeps Going Off (How to Fix)

The Toyota Prius is a relatively small hybrid Toyota vehicle that was one of the first of its kind. Some Toyota Prius’ didn’t come standard with an alarm, whereas others did. But, if the alarm on your Toyota Prius keeps going off, here is how to stop it from happening.

Rear car brake light turning on

Overall, the fob is faulty or running low on battery, the door, boot, or bonnet door sensors are faulty, or the car battery is faulty or the battery terminals are not connected properly. First see if the boot, bonnet, or door open lights are on when they’re all closed, then do the following.

If one of these lights are on then take a look at the connection where it latches closed. There can be something stuck in it that is preventing it from closing properly. Otherwise, the sensor will need to be repaired or replaced by a mechanic or your Toyota dealership.

If it’s not that, then inspect the battery to see that the terminals are connected tightly, and there is no visible corrosion or excessive grease or dirt on them. Corroded battery terminals are very easy to fix by using any kind of vinegar. But, the battery might not be holding a charge or is not providing enough voltage.

Most big name auto parts stores like Autozone will test your car battery for you if you take it to their store. Finally, replace the battery on your key fob. It’s very inexpensive and easy to do yourself.

If it’s still not working then the key fob may be faulty and you will need a replacement. Take your Toyota Prius to your Toyota Dealership, they can identify what the issue is, and/or replace your key fob.

Top Reasons Why Toyota Prius Alarm Keeps Going Off

Car mechanic with wrench

There are some main reasons why the alarm on a Toyota vehicle will keep going off. Here are the top most likely reasons why the alarm on your Toyota vehicle keeps going off.

In general, there is an issue with the car battery, the door, trunk, or hood sensors is faulty, there is an insect inside your car, the interior sensor is on, the fuse for the alarm in the fuse box is faulty, the key fob is faulty or the battery is nearly flat, or the alarm is set too sensitive.

There are 6 reasons in total, below I have broken down each of them and explained why each reason causes the alarm on your Toyota vehicle to keep going off, and how to troubleshoot each of these reasons so that it no longer happens.

1. The car battery terminals are loose/dirty or it’s faulty

The alarm system for your Toyota car is powered by your car battery. When the connection between the battery and the electronics in your car is disconnected it will cause the alarm to go off. If the terminals on your car battery are rusted, or a bit loose it will disconnect and reconnect the electricity to the electronic components in your car, which will trigger the alarm to go off randomly.

Also, if your car battery has trouble holding a charge, it may not be supplying a consistent amount of electricity to your car alarm. Pop the hood and take a look at the battery and the battery terminals.

If you can see the terminals are corroded or loose then clean them and tighten them.

After that, if the issue persists then you should ensure your battery is holding a charge properly. It can be tested yourself but most auto accessories stores such as Autozone will test car batteries free of charge. Otherwise you will need a voltmeter to test if the battery is supplying enough power using the method shown in the video above.

2. One of the door sensors the trunk sensor or the boot sensor is faulty

There are sensors for each of the doors, the trunk, and the boot. They detect when these are closed. If they are a bit faulty, or dirty it will tell your alarm that a door, the boot, or the truck is faulty when it is not.

To test for this sit in your car with all the doors closed and see if the open door light is on, or if the open boot, or open trunk light is on. If one of them is, then the latch sensor latch is dirty, or faulty. If your car only has an open door light but doesn’t specify which door, then inspect each of the door latches to see if any of them are dirty, or if anything is stuck in them. Do the same for the trunk and the boot, if these lights are on.

Otherwise, it means the sensor is bad, and you will need to have a mechanic repair or replace it. Or, take it to your Toyota dealer to have them repair it.

3. The interior sensor is getting triggered by something inside the cabin

Some Toyota vehicles such as the Toyota CH-R have what are called interior movement and perimetric sensors, which can be turned off temporarily by pressing the button for it when you leave your car. Sometimes a large bug such as a moth can trigger it to keep going off after you turn it off. Ideally, it’s better to have the interior sensor turned on for security.

But, if you’re having a hard time finding the bug that is triggering it then it can be a good idea to turn the interior sensor off for the night, especially if you park your car in your garage. Or, simply remove the insect or bug.

4. The fuse for the alarm is faulty

As you may know there is a fuse box for cars. It’s a small self-enclosed box about the size of a car battery. Inside there are fuses for each of the different electrical components.

If the fuse for your car alarm is faulty it will cause the electrical current between your car battery and the alarm to disconnect randomly. It’s possible to just take out the fuse and leave it out. If you do, in virtually every case your Toyota car alarm will continue to work. Under the lid for the fuse box has a diagram which has labels for each of the fuses.

The fuse you want to remove is: S-horn. It stands for security horn. It’s usually next to the horn, which is for your actual car horn. Simply pull it out. But, after doing so ensure your car alarm turns on and off.

5. The key fob is faulty or the key fob battery is nearly flat

This reason only occurs if the alarm goes off when you turn the alarm on and off. If the battery on your key fob is running low every time you use it to turn the alarm on and off it will set off the alarm.

This step is very easy to fix, and you simply need to swap out the battery for our key fob.

6. The alarm is too sensitive for where you park your car

Car alarms have a particular sensitivity which can be adjusted. Some people park their car in a place that will cause the alarm to go off. For example, on a cobble road, or on a busy street.

If that’s the case, passing cars, especially bigger cars and trucks can trigger your car alarm to go off. The sensitivity of a car alarm can be adjusted. However, it involves taking apart the area under the dashboard.

Which is a bit tricky unless you have experience working with tools. If you do park your Toyota in an area where the alarm is easily triggered then it’s a good idea to take it to a mechanic or your Toyota dealer and ask them to adjust it.

Copyright protected article by Know My Auto and was first published on Feb 20, 2023. .

General Fix For Toyota Prius Alarm That Keeps Going Off

Hybrid car parking in lot

A very inconvenient issue not only for you but possibly for your neighbors is if the alarm for your car keeps going off. It’s clear when this happens that there’s something wrong with it.

In general, inspect your car battery to ensure that it’s connected properly, the terminals are clean, and test it to check it’s providing enough power. The sensor for the door, hood, and trunk can be faulty and they need to be repaired or replaced. Or, there is an insect on the interior of your car.

In the article above, I covered the top reasons why your Toyota car alarm keeps going off. As well as, why they cause your Toyota alarm to keep going off, and how to fix each of these issues.

How To Reset Toyota Prius Alarm

Car mechanic fixing engine

With most electronics when you restart them it fixes a range of different issues. It’s possible to reset a Toyota alarm. Here’s how to reset your Toyota alarm when it keeps going off.

In general, you need to disconnect and reconnect the battery to reset your Toyota alarm. Doing so disconnects the power to the alarm which shuts down the internal computer. If the alarm keeps going off then it indicates a different issue, below are the reasons why your Toyota alarm keeps going off.

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Either the alarm is not getting enough power from your car battery, or the sensors for the door, trunk, or hood are faulty. Also, there can be an insect or small rodent in the interior of your car that is triggering the internal sensor. I have provided all of the reasons why the alarm on a Toyota vehicle keeps going off, as well as the troubleshooting steps to fix each of them.

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KnowMyAuto is the sole owner of this article was published on Feb 20, 2023 and last updated on .

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