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How Car Alarm System Works plus FAQ

 what is car alarm systemA car alarm is a gadget that triggers on to alert you when an intruder attempts to tamper with your car. It is programmed to make a loud noise enough to sensitize neighborhood of an impending danger or tampering happening around.


Due to high rate of insecurity and car theft in particular, many car owners today have one type or the other car alarm installed in their vehicle as a preventive measure.

A car alarm is built with sensors connected to a siren which generates loud noise immediately the connection is broken or tampered with.

Our article is to enlighten you step-by-step on how car alarm system works should you decide or are contemplating of installing one in your car.


Woman hand unlocking a car


How do Car alarm system work?

Not only could a car alarm be triggered to make loud noise if car theft is about to be carried out as many modern cars now come with car alarms that uses several sensors to detect motion, noise and even impacts around the car.

There has been a significant reduction in car theft and car-related crimes recently in the United Kingdom due to the renewed awareness demand for workable car alarm systems and its attendant usefulness even though some are of the contrary opinion.

Car alarms are of different types, specifications and usefulness. Some are easy-to-install with effective car door sensors while varieties of others are complicated yet sophisticated proximity alarm systems that detect and report just any impact around your car.

You may be wondering how they work? Are you not? Do not worry as we will explain to you how car alarms work and the technology employed in them to safe keep your vehicle in this guide as outlined.


The Rudiments of a car alarm

There are many parts into which a modern car alarm is broken ranging from computer part, the receiver that read signals from your key code, the loudspeaker or siren and sensors of various degrees.

Car alarm works in a very simple manner. Just switch on the alarm to send a signal to the sensor to give you a sound that signals an activation. The car alarm system remains very silent and unnoticed until a threat or unusual activity is recorded on or around your car.

Alarm fitted to expensive cars nowadays comes with between two to ten sensors compared with what it used to be before when they are built with just door sensor, shock sensor or a tilt.


Car theft and break in

Different types of car alarm trigger

The alarm Sensors:

Alarms today are built to respond swiftly to various but different security challenges such as breaking in through the car door, damage as a result of object or even unusual loud noise within the car vicinity or any other impact that may lead to any car crime or actual theft.

These sensors are connected to the alarm system’s computer to signal the moment a potential thief or intruder activate it to alert you or the security personnel within the area through a loud noise.

The door sensor:

These are the most common type of sensor used in modern car alarm system. When they are activated, or as a thief opens the car door, a signal is sent from the sensor to the system blaring the siren attached to call attention.

Using the door sensor is of importance since most thieves will want to use key (master key sometimes) to open your car’s lock to enter the vehicle except they desperately break the window to gain entry or tow away the vehicle.

The Impact or shock sensor:

This is equally important as it can both stop a thief from opening the car’s door or prevent him from breaking the window as it detects hits and other impacts on and around your car like the shock of hitting the car’s window to gain entry.

A bashing or minor hitting of your car when parked by another vehicle accidentally or unknowingly could be strong enough to trigger the alarm and produces alerting noise.

A microphone sensor:

Obstructs thieves from breaking into your car by sending signals whenever a loud sudden noise such as hitting of the door or window smashing occurs, even if they gently do the breaking using less impact or object.

This gadget accounts for all alien noise within certain perimeter to your car especially sudden unusual ones that could indicate a break-in.

A tilt sensor:

Most often, sensing that there is alarm system installed, thieves may decide to just use a tow truck to silently move away to a safer place, dismember it and sell to unsuspected buyers in parts.

When a tilt sensor which is installed to monitor your car’s angle is installed, its sensor alerts the computer that your car’s angle has changed and the alarm is automatically activated.

Mercury in the sensor conducts electricity to conduct its flows from one side to the other activate the switch and triggers the alarm.

Another sensor is proximity sensor which are also known as perimeter scanners that works by scanning your car’s surroundings to detect new cars just parked, movements within it and so on. This type of sensor is, in most cases not absolutely reliable as they can give false alarms since all they monitor and report is activity around your vehicle, whether counterfeit or genuine.


Masked teenager breaking into a car

What can trigger car alarm?

Shock or vibration sensors can trigger car alarm when someone is attempting or something is moving closer or gaining access to your vehicle. The closer the object or person to your car, if installed, the more active the sensor will react.


Will car alarm come on if window is broken?

If you install the impact or shock sensor fitted car alarm, yes it will. If it does not, it means something serious is wrong with the installation and as such the earlier you run a check either personally if you can or through a professional the better to prevent car theft or damage.


thief stealing car

What can make car alarm go off for no reason?

Coming up of a car alarm is the normal activation of what it was initially installed to report, so it is normal indicating that the installation is perfect and the sensors are working as expected.

Depending on the type of alarm system installed, it may be that something had forcefully hit the car or unusual loud sound like bomb blast is made around the car.

However, touching or grounding wire in the installation parlor may cause it if there is no threat within the car location that is suspected to have triggered the noise, so run a check properly.


How long will a car alarm go off for?

Car alarms can run make usual normal noise, beeps or siren sounds for as much as 3 to 4 minutes before going off. However, this is dependent on the type of alarm system you installed as specified in the manuals.


Can car alarm drain your car battery?

If installed appropriately or are fitted directly by the car builders from factory, car alarms do not drain much power from your battery except the installation (if your car has no factory fitted and you decide to install one for your car) is wrongly done, then it can consume much power due to some irregularities.

This may range from continuous ringing of the alarm without resetting itself (if it can automatically do that) or ignored by the owner and allowed running for a long period, then your battery will obviously be drained.

Sometimes, a weak battery on which a sensitive alarm triggers repeatedly could drain such with no power left in it.



Most of the above rudiments on how car alarms are designed to respond to a variety of different security threats and the modalities of how they work, if painstakingly followed will assist you in making a choice of which sensor is good for your car and ultimately enhance your car’s security at all time to the barest minimum.

We hope you are now enlightened on how car alarm system works, if you have a comment or question, leave it in the box below, we will be glad to hear from you.