920-499-4519 | Located in Green Bay, WI


How Car Alarms Work

How Car Alarms Work


According to the FBI, a motor vehicle is stolen and/or broken into every 44 seconds in the United States. Recent reports show that over $4.3 billion is lost every year due to vehicle theft, which is why more than ever, drivers need to make sure their vehicles are secured with a car alarm.

What is a Car Alarm?

The main purpose of a car alarm is to prevent the theft of your personal belongings within the vehicle and to prevent the theft of the vehicle itself. That said, not all car alarms are the same. Some are triggered by different actions and have different features. OEM car alarms tend to have basic features compared to aftermarket systems.

OEM vs Aftermarket

OEM car alarms typically come with basic car alarm features. These features are usually limited to 1-way remote door locks, 1-way remote start, starter/injector kill and horn trigger.  Most are designed only to prevent vehicle theft and are not designed to protect your belongings.

Aftermarket alarm systems offer a wider array of components and features that can be added on to beef up your security. The addition of an aftermarket car alarm using just the basic features can significantly increase your vehicles security.

Components of a car alarm

There are three main components of a car alarm:  The control unit or ‘brain’, the siren and the remote/fob/telematics for controlling the functions.  There are also a multitude of accessories available to customize the alarm for your needs.  These are all outlined below.

It’s important to note that car alarms are not going to completely eliminate theft and intrusion. However, by installing a security system with additional sensors and features such as 2-way remote alerts, you can significantly deter intruders from messing with your vehicle.

Alarm brain/control unit

The car alarm brain is essentially a computer that receives and sends commands, and is the main component in an aftermarket alarm system. The brain gets its power from the ignition harness or the battery but can also be protected with a battery backup for extra security.  All of the components in the system are connected to the brain; and the brain monitors all of them constantly while in an armed state.


An aftermarket siren provides a significantly louder noise than a OEM car horn. This will bring more attention and lessen the chance of a thief sticking around while the siren is going off.

Remote transmitter

Remotes and key fobs are used to send lock, unlock, and trunk release commands to your vehicle. A 2-way remote or fob can receive confirmations back from the brain confirming commands or alerting you of possible theft in progress.  You may also monitor and control your vehicle by using your phone if you have a telematics module such as DroneMobile.

Tilt/shock sensor

The tilt/shock sensor detects impact and vehicle tilt. The shock sensor will be triggered when there is impact to your vehicle. The tilt sensor is will trigger the alarm if your vehicle is being towed or jacked up. This is a feature that is generally not available with OEM alarms, and is available with all Compustar security systems.

Interior LED light

An interior LED light will let people know that you have an aftermarket security system. Car thieves are not as likely to attempt theft of your vehicle if they know you have a security system installed.

Door trigger sensing

Door trigger sensing will trigger the alarm if the doors of your vehicle are opened when the security system is armed. Door trigger sensing is not just limited to driver and passenger doors; it can also be used to detect trunk/hatch entry as well as hood entry.

Additional features that may come with an alarm

There are additional features that may come with or be added to an aftermarket alarm.  Some of these features can be added by simply connecting a wire or turning on a setting in the brain.  Others require additional parts and labor.

Popular Compustar Security Systems At SOUND WORLD GREEN BAY CALL 920-499-4519 FOR APPOINTMENT

  • CS720-A – 1-way w/ up to 200 feet of range
  • PRIME 705 – 2-way LCD w/ up to 1500 feet of range
  • PRO T11 – 2-way LCD w/ up to 3-miles of range

Call Us: 920-499-4519

1850 W. Mason St, Green Bay, WI 54303