A car alarm is a piece of equipment that makes a loud noise when someone tries to steal your car [source: Macmillan]. According to the FBI there is a car stolen every 40 seconds in the United States with an average valuation of $6,500 per vehicle [source: RMIIA]. Most cars today have some form of car alarm installed in them. A car alarm consists of sensors connected to a siren in such a way that when the connection is broken the siren starts wailing. We will now attempt to show you how to install a basic car alarm system.

  1. Attach the siren to any solid metal surface under the hood. Place the horn of the siren facing down, so no water will get into it.
  2. Drill a hole in the rubber firewall of the car. Thread the siren's wire through that hole into the passenger compartment of the car.
  3. Place the alarm's power line near the car battery ready to be attached later. (Don't attach it just yet.)
  4. Attach a fuse to the wire mentioned above, that you will be attaching to the battery later.
  5. Check the alarm's instruction manual and mount the shock sensor.
  6. Drill a hole in the dashboard for the LED indicator.
  7. Feed the LED indicator wire through the hole. Secure the LED indicator into place with double-sided mounting tape.
  8. Locate the wires that connect to the light button on the door. That's the button that turns on the light in the car whenever the door is opened. If you have power locks, locate the wire that connects to the power locks, as well.
  9. Connect a sensor to these wires.
  10. Secure and attach all input and output wires to the alarm module.
  11. Mount the module under the dashboard.
  12. Bundle together all the wires and stuff them under the dashboard.
  13. Connect the alarm power wire to the car battery and your alarm is armed and ready to go [source: Commando Alarms].