How to Install Car Alarms: A Complete Guide

How to Install Car Alarms A Complete Guide

Just bought a recondition vehicle? Or decided to opt for additional security in your newly bought car?

A car alarm installation to your vehicle is not a bad idea. It may seem difficult to install car alarms but proper preparation and information can help you do it yourself. 

So before you turn the first screw, read this complete step by step guide.

Planning the Installation

A proper plan of installation can save your hours. Gather your car's manuals, find the locations, and other documents before starting.

Make sure that your doors trigger the indicator. If any of them doesn't trigger, the alarm will not be effective.

Most alarms are equipped with optional pin switches that make the alarm rings when a door opens. They can be an alternative if your door doesn't trigger.

Find the wiring diagram from the service manual and note the panels should be removed. Learn where to connect the plan from the wiring layout.

Remember one thing- a better plan can ease your whole process.

Gather necessary tools

After owning the basics gather necessary tools like wrenches and an electric drill and screwdrivers.

You'll need a panel removal tool to get behind the places you may access. 

Gather a crimping tool or a soldering iron tool to make secure wire connections. Electrical tapes can be used to protect the connections.

Use a meter to check the function of each wire when activating sensors if you don't find the wiring diagram in the user manual or internet search.

Use a voltmeter instead of a test light. Test lights can damage the sensitive circuits by drawing much current.  

Installing the Car Alarm Unit

Now it’s time to install the car alarm unit. Do the installation according to the step by step guide below:

1. Remove the necessary panels to access the wires needed to hook your alarm up. Commonly, the panels near the dash on the driver's side or under the steering wheel.

    Each car has different panels to remove. take help from your car’s manual. 

    2.Mount the car alarm in an invisible place. Remember- the harder it is to find, the more secured it will be. A thief can temper it if it is visible. 

      Be careful before running a screw. You may screw into other surfaces or wires accidentally.

      3.You have to make a new hole to run a wire to the siren from the alarm. You can skip this step if you have an existing hole in the firewall.

        If you're about to drill a new hole, make sure you'll not hit any other parts.

        4. Run a wire into the firewall to connect siren to the alarm. Your wires can be damaged by friction or sorted out. 

          So, we recommend you to insulate the wire using rubber boot or to use silicon to fill the hole. Ensure the wire will not be kicked or tugged.

          5. Now, mount the siren in the engine bay or any other place on the firewall. 

            The voice coil can be accumulated by water so we recommend you mount it's face down.

            Mounting the alarm brain

            Mount the alarm brain under the dash or under a front seat. 

            Mounting it near the steering column is the most common. You'll get a good range of remote control because it's up high. The installation and service are easier because it is easy to reach. 

            The disadvantage of mounting it under the dash is an experienced thief can look there for the first time and can yank the wires out of the brain. 

            We suggest you find a less obvious place.

            On the other hand, mounting it under a front seat is easier. It is not obvious to a thief and isolated from any other electrical interface. 

            The disadvantages are your remote control range won't be good and your SRS system can be deactivated. And a splash of water can end up the brain.

            Mounting the siren

            The siren can be mounted under the hood in the engine block. Mounting it 18 inches away from the heat sources is recommended. 

            Try to mount it parallel or toward the ground, never with the horn up facing that cause the siren to malfunction.

            Some cars allow you to mount it to the inner fender panel. Select a place harder to reach by the thieves. 

            The siren wires route should also be away from the reach of a thief.

            Use sheet metal screws in case of mounting your siren to a metal surface and secure the siren with nuts and bolts mounting it to a plastic inner fender.

            Be careful before screwing the mounting surface. Do not penetrate brake lines, fuel lines, vacuum lines, and wires accidentally.

            Mounting the flashing LED

            Your security system is equipped with a little flashing light mounted in the dash or center console to warn the possible thieves that the vehicle has a security system and ready to wail in attempting to break-in.

            Our suggestion is to mount the LED in a highly visible area from all sides of the vehicle. 

            Before drilling the hole make sure that you've checked the requirements. 

            Ensure sufficient space and path for the wires.

            Wiring the Connections

            Follow the steps below and wire the connection DIY.

            1. Equip a valet switch to wire off the alarm module to disable alarm features when the car is in use. It will be needed when you leave it to the workshop.
            2. Equip a LED light that indicates the alarm is armed. Mount it to the dash and be careful not to hit any other parts when drilling the hole.
            3. Extend the range of your remote control with external antennas to receive signals from outsides and it should be transmitted to the alarm module. Glass mount antennas are the most common and no drill holes are needed.
            4. Now connect the siren. It has two wires; one positive and the other is negative. connect the positive one to the alarm and the other one to the ground.
            5. Then connect the alarm sensors that help to signal that something is wrong and the siren sounds.
            6. Hook the power wires up to a constant power source to activate it and replace the panels on your vehicle in a correct order to fit them properly together.

            Connect the battery and test the alarm

            After connecting the power line to the battery allow the alarm system to power up as the car starts. Check the system’s manual if any additional calibration is needed.

            Check the system if it is working properly. If your system has no remote, jostle the door when the alarm is armed.

            If you find your system working properly, bundle the wires using electrical tape to secure connections.


            Hopefully, this guide will help to install a security alarm system in your car. Once done, you’ll be at peace that your car is secured from the criminals.

            If any of the steps becomes harder for you to do, take help from professional mechanics.


            How much does it cost to install an alarm system in a car?

            There is a broad range of car security systems. An advanced car security system will cost you from $100 to $450 and more. The cost depends on their functionality.

            Do car alarms really work?

            80% of car alarms can be disabled by thieves. But a good alarm with motion sensors can save your car.

            What triggers a car alarm?

            If the sensor detects a potential movement or vibration, it sends signal to the brain that makes the alarm ring.

            What causes car alarms to go off for no reason?

            Car alarms may go off for various reasons. If the key fob doesn't function properly, it may send wrong signals to your car. It may cause your car's alarm to go off for no reason. The hood latch sensor, car battery, and corroded battery terminal can also be responsible for that.



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