Everything You Need to Know About Car Alarms

Everything You Need to Know About Car Alarms

One component of owning a vehicle that’s often overlooked or taken for granted is the car alarm.

As the name suggests, car alarms go off if a car is exposed to potentially dangerous circumstances, such as light bumps or external factors such as thunder. Sometimes, one can’t help but wonder: how exactly do they work?

In this article, we’ll discuss how car alarm systems work. Read on below to learn more.

More about Car Alarms

Since an alarm can go off under different circumstances, you might think that all car alarms are the same. That’s very far from the truth, and we’ll debunk the misconceptions about them.

Many people don’t know that all kinds of car alarms rely on one thing: the sensor. The sensor is what detects possible disturbances that can cause an alarm to go off. Another thing that many people don’t know is that there are different types of sensors.

The different variants of a car alarm sensor are as follows:

Door Sensor

While radically different from each other, older and modern cars can still have one thing in common: a door sensor.

As the name suggests, the door sensor is installed in the doors. You might know how this works because all it takes is an active alarm system and opening the car door, locked or otherwise. If this happens, signals will be sent to the car’s computer, which will prompt the alarm to go off.

Microphone Sensor

If a car is being stolen, one of the few ways a thief can break in is by smashing the window before unlocking the door and hot-wiring the car. For this reason, the microphone sensor becomes handy.

Microphone sensors work in two ways:

  • If there’s a slight bit of noise when a car’s surroundings are silent, it alerts the computer and sets the alarm off.
  • If a car is in an area with a lot of noise, the microphone sensors will record the sounds, and if there’s a sudden spike, the computer will be alerted and the alarm is set off.

Proximity Sensor

These sensors are more prevalent in modern, high-end cars. A proximity sensor just stays as is until it detects physical activity that’s near the vehicle. This alerts the computer and sets off the car alarm.

Shock Sensor

Also known as the impact sensor, this detects any physical disturbances to the car. A shock sensor works by alerting the computer when the vehicle is hit, or the windows are broken, which sets off the alarm. Aside from that, this is also the sensor that sounds the alarm when shock waves from a distance are generated.

Tilt Sensor

One of the more ingenious ways of stealing a car is by towing it away. Luckily, this won’t be a problem if a vehicle has tilt sensors installed.

Tilt sensors detect minimal angle changes in the transverse axis, which runs across the car’s width via the centre of mass. The tilt sensor is a tube that’s part of the circuit that’s filled with mercury. The mercury inside is flat at ground level, which allows the charge to flow, closing the circuit. When the car is tilted, the mercury goes to one side, which breaks the circuit. This alerts the computer and sets off the alarm.


In essence, car alarms are a security measure to protect a car from theft. You must always check if your car alarm’s sensors are in proper working condition and get them fixed or replaced if they’re not. If you leave them be, then you may not have a chance of knowing that it’s being stolen until you come back to it, only to see that your car isn’t in the same place you left it.

If you’re looking for car alarm systems in Sheffield, Vehicle Security & Electrical offer a wide variety, all of which can fit any car with additional components to increase security. Simply go to our website and take your pick!

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