What to Do When Your Car Alarm Keeps Going Off Randomly

Having your car alarm going off is always a hassle. It’s loud, obnoxious, but there to help attract attention if any suspicious activity occurs and prevent your vehicle from being stolen.

In the 21st century, there are plenty of car alarms that can fit your needs and increase the security of your car.

However, if you’re having issues with your alarm going off randomly, don’t worry. In this article, we’ll tackle the basics of a car alarm and what triggers it, as well as how to prevent future problems.

Car Alarm Basics

According to the National Insurance Crime Bureau (NICB), one car was stolen every 36 seconds in 2020. In other words, that averages to about 870,000 vehicle thefts.

With how often this crime occurs, having a car alarm gives the owner peace of mind at night or if they don’t have the security of a garage. A car alarm has three to four major components to function, including a computer, a keycode receiver, a loudspeaker, and several different sensors, such as door, shock, proximity, or tilt.

Depending on what model car you have, there could be more advanced abilities in the alarm. Older versions don’t rely on the technology newer cars have.

What Triggers a Car Alarm?

Generally speaking, a car alarm is triggered whenever the motion sensors detect a bump or other impact. The alarm will go off if one of the doors is fiddled with, too. (Sometimes, even weather can activate the alarm, such as a close clap of thunder or a powerful gust of wind!).

Yet, if your system is faulty, then an alarm can go off without needing one of these prompts.

Typical Car Alarm Problems

Below, we’ll address some of the typical car alarm problems, possible causes, and how to fix them. You won’t have to worry anymore about losing sleep or annoying your neighbors.

1) The Car Alarm Keeps Going Off When I Open the Door

Possible Cause

If your alarm goes off when you open the door, your lock sensor may not be functioning correctly. This device consists of two wires (an open and closed circuit). A door lock sensor is installed inside the door lock actuator. This sensor acts up during rainy weather when water seeps in. Additionally, they can fail through normal wear and tear and are prone to breaking over time.

How to Fix It

Sealing the door sensor with protective grease is helpful. You could also check if it works properly via your key fob. When the door switches, listen for any unusual or noticeable buzzing and humming sounds, which will help narrow down the problem and determine its origin. Lastly, you could use a scan tool to discover what part requires replacement.

2) Why Does My Car Alarm Go Off When I Open the Door from the Inside?

Possible Cause

A weak or overly-sensitive sensor connection could be the perpetrator of this issue. The variety of sensors, such as the door and shock-sensor, are all linked together. Another way to think about this would be if one of these goes off, the alarm will trigger. The model of your car could have either fixed or adjustable settings, and the sensitivity depends on what type of alarm system is installed in your vehicle.

How to Fix It

Check the connection between them. If they’re sourced from the main battery, then that helps determine how to fix this problem. Of course, if you’re unsure, take your car to a shop and get a mechanic’s opinion and advice.

3) Why Does My Car Alarm Keep Going Off When I Start the Car?

Possible Cause

Poorly installed or circuitry problems may be causing your alarm to go off when turning the ignition key. If the wiring is faulty, the alarm will be triggered due to this disconnection.

How to Fix It

Look for other related issues, such as if your headlights flash and horns blare because that indicates the wires are not circuited properly. If not, the alarm is going off because of another problem elsewhere. (Keep reading to find out how you can bypass the alarm and start your car).

4) Car Alarm Randomly Going Off at Night

Possible Cause

Low battery levels are often the main culprit behind the loud, annoying alarm. Surprisingly, one of the main functions of the battery is to warn when it is low, making the alarm go off.

How to Fix It

Check the running voltage with a voltmeter. If the voltmeter registers less than 12.6V, or another specific number given in the manual, you might have to jolt the battery or have the battery replaced entirely.

5) Car Alarm Goes Off When Unlocking with Key

Possible Cause

A nonfunctional key fob could be giving you problems when unlocking. A key fob is the controller in keyless entry systems and sends a distinct signal to the receiver to lock and unlock your car or even start the ignition. When not functioning properly, guess what happens? You got it—the alarm goes off.

How to Fix It

Replace the battery after long periods of use. This is the best way to ensure that the alarm will no longer go off when unlocking your car with a key fob.

You could also reset the key fob or take it apart to look for misplaced buttons or broken connections. If you’re aiming to reprogram the controller, it’s best to seek the help of a professional.

6) Car Alarm Going Off While Driving

Possible Cause

A defective hood latch sensor goes off regardless of if you’re driving or not. This part consists of an electrical switch that deciphers when the hood is opened or closed. When the latch is either of the former, it clicks a warning light on. Yet, when this specific sensor is defective, the alarm blares instead. Hearing this sound would be terrifying if you were driving, causing more problems and risking more accidents.

How to Fix It

Keeping your sensor clean of dirt, debris, or engine grease limits malfunctions and decreases false alarms. Not only that, but your vehicle will be better protected from theft or damage. Use a brake cleaner and cleaning brush often. Nonetheless, if the sensor is damaged or tampered with, replace it immediately.

7) Car Alarm Keeps Going Off After Battery Change

Possible Cause

After you or the mechanic changes the battery, your vehicle undergoes a reset. The alarm, after sitting motionless for some time, also resets.

How to Fix It

You should lock all the doors with a remote or key, then unlock the car. Once restarting, make sure all the doors are shut and the key is removed from the ignition, and you won’t encounter this issue anymore.

8) Car Alarm Keeps Going Off in Cold Weather

Possible Cause

Cold weather often means rain or snow, which in turn means corroded or rusted battery terminals. Your battery isn’t low, but the rust makes it think that there is not enough power to supply the various car parts. Therefore, the alarm sounds.

Moisture and salt or even improper replacement could make your battery cue being undercharged. On the other hand, corrosion happens when the battery is overcharged.

How to Fix It

Clean the battery with a commercial-grade cleaning agent and a wire brush if the damage is minor. If your battery underwent severe rust or corrosion damage, replace it entirely. Remember to wear protective gear while doing so.

Frequently Asked Questions

Here, we’ll answer some of the most frequently asked questions about car alarms.

Can a Low Battery Cause a Car Alarm to Go Off?

Yes. As stated previously, a low battery is one of the main causes for an alarm to go off.

How Do I Bypass the Car Alarm to Start the Car?

When your alarm sounds, most times, you’re able to start the ignition. If not, try the ACC (accessory) position, or where you can play the radio without the engine running.

Furthermore, you can try locking, then unlocking your doors. Both are possible solutions to bypassing the alarm and starting your car.

How Do I Disable My Car Alarm?

There are multiple ways to disable your car alarm, the first being removing the alarm fuse. Be sure to detach the battery to reduce the possibility of electrocution.

Another would be to pull the wires, but only if you installed the alarm or are familiar with the system. Normally, they are positioned under the steering wheel, but this process is not recommended unless you have professional guidance.

Lastly, you could remove the alarm system completely or partially. Whatever you decide, address the alarm as soon as possible.

How Do You Set Off a Car Alarm on Purpose?

Key fobs have a panic button which is colored red or orange and labeled with a horn symbol. Pressing it sets off your alarm on purpose. Knowing how to cue your alarm manually is helpful if you think your car is being tampered with.

Hopefully, this article provided proper guidance on troubleshooting why your car alarm keeps going off randomly and how to fix it.

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Author: Dave Johnston

Dave Junior is a hands-on automotive technician with experience in performing service, diagnostics, and repairs on domestic and imported vehicles. He enjoys writing and sharing his knowledge far and wide.

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