How to Install a Car Alarm

Most do-it-yourself car alarms are simple devices that provide minimal security. If you don't want the hassle of installing the alarm yourself, look for an automobile alarm and security company that will do the job.

Instructions

Difficulty: Moderate

Preparing for the Installation

1. Gather materials. You will need scissors or a knife, crimps, solder material, solder gun, test light, drill, screw bit, screws, tie wrap, double-sided mounting tape and a voltmeter.
2. Read the installation manual that comes with the alarm.
3. Call the tech support number for manufacturer of the alarm and tell the tech advisor what kind of car you have. Ask what kind of locking system your car uses and what color wire to connect to in order to interface the lock/unlock feature of your alarm,
4. Ask the advisor how to hook up the relay for the door lock feature, what color wire to connect to for the starter disable feature, and how to hook up the relay.
5. Ask how to set up the voltmeter to test the door lock wires.
6. Ask how to access the factory door triggers.
7. Determine where you intend to place the components by referring to the installation manual.

The Installation

8. Mount the siren to a solid metal surface under the hood. Point the horn of the siren down toward the ground so that moisture cannot collect inside it. Drill a hole through a rubber grommet in the firewall of the car and feed the siren's wire through that hole into the passenger compartment of the car.
9. Connect the alarm's power wire directly to the car's battery. Feed the wire through the rubber grommet on the firewall and into the passenger compartment of the car.
10. Put a fuse on the power wire next to the battery. Check the installation manual for the fuse size.
11. Mount the shock sensor as described in the manual.
12. Drill a hole in the dash where you intend to place the LED status indicator. Feed the LED's wire through that hole and place the double-sided mounting tape to the back of the LED and place it over the hole in the dash.
13. Locate the wires that work the car's power door locks.
14. Connect the door-lock relay to the lock/unlock wires and connect the alarm wire to the relay in the manner described by the tech advisor.
15. Using the advice of the tech advisor, locate the wire that works the courtesy light if the alarm has current sensing.
16. Connect the current sensing line from the alarm to the courtesy light wire.
17. Locate the factory door triggers if the alarm does not have current or voltage sensing.
18. Connect the factory door trigger to the alarm.
19. Find the starter wire on the steering column some inches below the starter switch. Cut the line and connect the starter disable relay. Connect the starter disable wire from the alarm to the relay.
20. Mount the valet switch somewhere under the dash.
21. Connect all the wires to the proper inputs and outputs of the alarm module.
22. Mount the module to a sturdy surface under the dash using the drill, screw bit and screws.
23. Use the tie wraps to secure the wires of the harness and stuff it back under the dash.
24. Arm the alarm and test its performance.

Tips & Warnings

• If you intend to install an alarm with a current- or voltage-sensing feature, ask the tech advisor what color wire works the courtesy light and where you can access it.
• When you arm the alarm, the doors should lock. Disarm the alarm, and the doors should unlock. Arm the alarm again and open a door using the key. The alarm should sound. Disarm the alarm, close the door and re-arm the alarm. Hit the car as hard as you can with your hand. The alarm should sound. Disarm the alarm. Arm the alarm and try to start the car. You should be unable to start the car.
• If the alarm does not work properly, check your wiring and connections and try again.