The five-fold path to security enlightenment

There are some killer top-of-the-line systems out there today. I like to have the great gear as much as the next enthusiast, but here’s the news: you may be better off buying more add-ons and less alarm! If you are protecting audio gear, wheels, and other custom accessories, consider the options below when determining your final budget. I personally believe that a middle-of-the-road system with some of the features discussed here is more secure than a top-of-the-line system without the installation features to do it justice.

1) Pay dollars for sense

Almost every alarm in the world comes with an impact sensor (also commonly called a “shock” sensor). The original purpose of an impact sensor, as us old-timers remember, was to detect force being applied to the door lock cylinder on the outside of the door or trunk. This force is usually applied with a hammer.

I believe that good security requires a good impact sensor, properly adjusted. Unfortunately, most false alarms result from improperly mounted, poorly adjusted impact sensors. Adding a glass break sensor, a proximity sensor, or sometimes even a trunk pin switch or a window-mounted magnetic reed switch will let you set all your sensors to lower thresholds, and your false alarms will actually go down!

Since breaking tempered glass creates very different vibrations than hitting sheet metal with a hammer, almost every alarm maker has a microphone-based glass sensor. I have been using these religiously for over a decade, and as long as they are properly adjusted, they work well. I set mine so that one key rapping against the window will not trigger the system, but three or four keys will. (Remember to roll up your windows if you have glass-break sensing, and I do not recommend it for convertibles.)

Many shops will nowadays recommend a proximity sensor over a glass microphone, and I agree with that recommendation if you have a convertible, or if your budget has enough room. However, proximity alarms might eat up enough of your budget to prevent you from taking advantage of some of the other points below, so think your decision through!

2) Learn the art of noise

Your system is intended to attract attention to any would-be thieves or burglars. In order to do its job, it must attract attention no matter what. Every alarm comes with a siren. I recommend paying additional installation fees to have the siren and its wires mounted out of easy reach (with newer front-wheel-drive cars, I prefer to mount sirens inside the ABS-molded inner fender). Expect to pay up to an additional hour of installation labor, but it’s well worth the money.

I also highly recommend horn honk, especially if the system has a dedicated horn output. Remember that the install price of a horn-capable system rarely includes wiring the horn, since so many customers want to save the few dollars it takes to do it right. Horn honk attracts lots of attention, especially in conjunction with a siren.

Finally, to protect your audio system, consider a piezo-type mini siren mounted inside your center air vents. The piercing sound, in such close quarters, does a great job of deterring would-be head unit thieves.

3) Keep your priorities straight

Keyless entry is very popular with modern cars. If your system has auxiliary outputs, you can have your shop wire what is often called driver’s door priority unlocking. While it does add to the cost and complexity of the door lock inteface task, it allows you to always unlock only the driver’s door when disarming, and unlock the rest by pressing a second button. The idea is to make it much harder for anybody to jump into your car with you. I really like this function for anybody that works in a retail situation, especially in malls.

While some alarms have circuitry to make this priority-unlock feature easier, almost any multiple-output alarm can accommodate this capability. Expect longer installation times.

4) Hold on to your power

Some alarm makers demand that the installer run power wires directly to the battery and some do not. No matter what system you have, your car battery will be powering your alarm. Make sure to get your battery some backup, either with a security-specific backup battery or a siren with its own backup battery inside. I personally prefer the separate battery, since it allows all your auxiliary noisemakers mentioned previously to keep going.

I also offer my customers the option of paying for additional installation time for maximum stealth routing of the power wiring and fuses. Every alarm system requires plenty of appropriate fuses, but make sure they are not too obvious if you are serious about your vehicle security.

5) Two is better than one

Starter kill has been around for years, and all the better install shops will conceal your starter kill relay pretty well. If your vehicle is a high-percentage theft target, you may want to consider taking a belt-and-suspenders approach to starter kill. For instance, many of my Acura Integra GS-R customers pay for an interrupt relay to be installed on the clutch-pedal interlock circuit. (This is the circuit which prevents starting without pressing the clutch pedal first.) The relay “fools” the vehicle into thinking that the clutch pedal is not being pressed, whether it is or not. Even if somebody has the time and technical savvy to bypass the standard starter kill circuitry, they probably won’t find both circuits.


Notice that every one of these takes more time and money. Make sure that the shop and the installer you ask to do this work likes the idea and understands what you want to accomplish, and your security will be second to none.

Looking at all the different sensors available for alarms today can be overwhelming. Proximity, impact, “glass”, motion, shock, “radar”…what do they do, and what should you expect from them? Here’s the scoop:

Impact sensors (also called shock sensors): These sensors are intended to detect damage to the vehicle’s sheet metal, primarily in the door lock cylinder area. In this case, damage means “what happens when you punch the locks out with a hammer and chisel”. Better sensors will also have a shot at detecting damage to the trunk lock, but trunks are so well isolated in some newer cars it’s not always a sure thing (the best way to cover your trunk is an impact sensor and a trunk pin switch). If someone tells you that your impact sensor is also going to detect breaking glass, take it with a grain of salt – breaking tempered glass creates a completely different vibration signature than striking sheet metal, and if your sensor detects both, I’d expect too many false alarms.

Many of these sensors operate on some sort of sympathetic resonance principle – while the exact technology differs from design to design (well, now it does, after some nasty patent litigation), the basic idea is the same.

How I test them: With the door closed, the windows up, and the alarm armed, I hit the door lock cylinder firmly with the side of my closed fist. If my hand hurts and the alarm does not react, the setting should go up. If barely touching the door gets me a full-blast alarm, the setting should drop. The sensitivity should be even from the left side of the car to the right side (reaching this goal may require sensor relocation).



Glass breakage sensors (also called audio sensors): This is a microphone with a basic analyzing circuit attached. It has only one job – reacting to the sounds of metal on glass and cracking glass. Any damage to sheet metal…well, that’s not glass, now, is it? Also, glass sensors hate open windows and sunroofs – if you leave the windows down, expect falsing. Back in the day, this sensor was the real deal (shock sensors of this period were basically a drywall screw and a ballpoint-pen spring, so glass microphones were “high-tech”). Alpine even had an alarm (the venerable 8122) with one microphone for each front door – the installer had to pull the door panels and install them inside! To be fair, those mikes were also intended to “hear” slim-jims before the door was opened. I still love glass mikes, as I believe they allow an installer to lower impact-sensor settings to a reasonable range, thus avoiding many false alarms.

How I test them: Use a set of keys – one key rapped against the front window should not set off the alarm, but three all at one time should.


Proximity sensors (also called “radar”and microwave sensors): These use a low-power microwave field to detect moving mass. The mass forces the field generator to work harder, as it were – and this shift in field generating difficulty is sensed. The bigger the mass, the farther away it is detected (hence, UPS trucks are detected from farther away than, say, your head). These are great for convertibles and Jeeps, and can play an important role in any full-fledged security system. If you choose a microwave sensor, make sure your alarm system has some sort of pre-warning feature – nobody needs to hear sixty seconds of full siren just because they walked past your car!

The early sensors could only elicit one reaction: full-blast siren. Most newer systems allow for multiple levels of reaction. Personally, my advice is that if your system will not support more than one level of response, you should not add a proximity sensor to it! Instead, buy a new alarm, preferably one which is designed to accommodate these sensors.

A few things to remember about microwave sensors:
· Many brands of window tint have metal flakes which effectively stop a microwave field. If you have tinted windows, keep this in mind.
· These sensors can be affected by radio installations at airports, transmission towers, some radar detectors, and microwave ovens.
· Since the field size can vary from summer weather to winter with some designs, check your sensitivity regularly.

How I test them: Note that while an ideal installation has even coverage on both sides, with some cars you just can’t always get what you want. Proximity sensors are very installation-intensive: if you want them to work just so, expect to pay for some additional installation test and trial time.

With all the windows rolled up, placing my face up against the front window, as if I were checking out your in-dash, should trigger the system’s warning response. I should not be able to trigger the full alarm response with the windows up –if I can, I would turn it down.
With one window rolled down, reaching into the interior far enough to get one shoulder inside should give me full siren response – this test should be tried on both sides.