Guide To Understanding What Triggers Car Alarms

Guide To Understanding What Triggers Car Alarms

It is important to understand just what triggers your car’s alarm safety system. Not knowing the ins-and-outs of your alarm system can lead to a detrimental lack of understanding and frustration in the meantime. Whether your car features a built-in alarm, or an aftermarket system, knowing how it works can add to your overall mechanical knowledge.

Improved car alarm systems have been shown to play a role in the frequency of car thefts across the world. There are many different types of car alarm systems, each of which contain both advantages and disadvantages. Here, we will examine some of the basics of what triggers car alarms, and go in depth as well.

Components of an Alarm System

Typically, car alarms feature around four distinct parts: a receiver, sensors, a simple computer system, and perhaps most notably, an auditory alarm system. As soon as a response is sent to the sensor, the alarm sounds.

One thing to keep in mind is that an alarm is active even when it is not going off. This is because the sensors have yet to pick up on any suspiciousness. Some vehicles feature up to 10 sensors, while others are equipped with 2 efficient sensors.


The sensors themselves provide direct input into the computer. This input is designed to pick up on what may in fact be, for example, theft. And these sensors pick up on a variety of vehicle intrusion methods. Whether a break-in via the door is occurring, or a powerful impact is made, the alarm can be triggered.

What many people don’t know is that alarm systems can also be triggered simply due to excessively loud foreign noises within the cars proximity.  Most car alarms typically utilize door sensors. These are the most common type of sensor. If the door is opened, or a door sensor picks up on any unusual activity, a signal will then be sent directly to the alarm.

Door sensors are ideal due to the fact that most cases of theft require tampering with the locks. Although a window can still be broken, at least a signal of alert is made.

Many cars are also equipped with what are called shock sensors. These also go by the name of impact sensors in certain cases. These sensors easily pick up on any impacts made to your car, or for example damage done to a window. They are able to immediately recognize when damage is done.

Like all other sensors, a signal will be immediately sent to the computer to trigger the alarm if impact were to take place. Although they are completely necessary to detect a different kind of threat, shock sensors are also frequently triggered when someone is leaning on a car, or if a door-ding in a parking lot were to occur.  Cars also contain microphone sensors.

At one point thieves began to take notice that if they were to debilitate a window through less forceful means, they could bypass impact sensors. Microphone sensors help to detect these cases where a window could be dismantled in an unaggressive manner.

Essentially, they are able to detect noises which identify as that of theft. It is not uncommon for high-end microphone sensors to be located in high-end vehicles.

Some microphone sensors are better than others. Many of the better ones are able to pick up on low frequency sounds that a cheaper microphone sensor would altogether ignore.

Some of the newer microphone sensors are able to pick up on the median sound levels located in and around a vehicle, so that they are not triggered unnecessarily. But as soon as a threatening change in sound occurs, a signal is sent to the computer triggering the alarm.

But what if someone were to attempt to steal your car, thereby bypassing all of the above sensors. This is where tilt sensors come in handy. Tilt sensors are able to gauge the angles of your vehicle, so that if someone were to attempt to tow your car away they would trigger.

Many of the newer tilt sensors are known for conducting electricity through the use of mercury. This mercury either flows in one direction or another when the car is tilted, thereby activating the sensor.

Although it is somewhat slow moving, it is incredibly proficient. The consistency of the mercury also helps to prevent any false alarms from going off. Therefore, when a tilt sensor is activated, it usually is accurate about the threat of danger.

Tilt sensors also have the ability to gauge where a car is parked to begin with. For example, if a car is parked on a hill, this will not activate the tilt sensor, for it will know that the driver intended to park the vehicle there.

But as soon as any additional movement is noted by the change in the flow of the mercury, a signal will be sent to the alarm systems computer. This makes mercury driven tilt sensors incredibly effective in modern car alarm systems. It also adds to the sensors proficiency in identifying any threatening changes due to the tilt of the car.  Newer cars make use of proximity sensors.

By scanning the perimeter of your cars parked location, they are able to gauge whether or not the activity in the area poses a threat. It is not uncommon for high-end cars to contain proximity sensors. It is also not uncommon for these sensors to siren falsely.

Depending on the quality of a proximity sensor, some misfire more than others. Although this can be annoying, ultimately is adding to the overall safety of your vehicle.

One is better off with proximity sensors as additional sensors to their security system than without. They are able to identify dangerous objects and their proximity to your vehicle. Sometimes they will even activate if an object becomes too close to your vehicle, without touching it.


Each of the components of car alarm security systems, add to the overall safety of your vehicle. As you can now see, they are each triggered differently and measure different threats accordingly. Typically, the more sensors the better. A good balance of each type of sensor, carefully placed, is what modern drivers can benefit from.

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