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Steal Stopping - Part One

Devising a cost-effective car security system.

By Michael Knowling

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At a glance...

  • Alarms v immobilisers - the advantages and disadvantages
  • Typical alarm and immobiliser features
  • Our AUD$250 approach to effective car security
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So you think because your car has a remote control alarm, it’s secure, huh?

Well it isn’t!

Think about this. You’re returning to your car after a late shift at work, you pull your remote and keys out of your pocket and – whammo – you get hit from behind. Not only are you injured, some low-life scum now has full, unrestricted access to your car.

Wave bye-bye.

And what if you’re somebody that leaves your keys on the kitchen table and often forget to lock the doors? All it takes is an unnoticed intruder and, again, you’ve just handed over full access to your car.

And don’t think that these scenarios don’t happen. They do!

Car Security – Back to Basics

Wander into any car security shop and you’ll be bombarded with talk of microwave and ultrasonic sensors, code hopping, all-black wiring and more.

Forget about all that for a moment. Let’s start off talking about the basics of car security.

Immobilisers v Alarms

There are two common approaches to car security – an immobiliser and an alarm.

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As its name implies, an immobiliser serves to disable your car’s engine. Sure, a thief can throw a brick through a side window and get into the vehicle but the upshot is they won’t be able to drive it away. Unfortunately, an immobiliser does nothing to protect the valuable goods inside your car – loose money, jackets, CDs and sunglasses are easy prey. Aftermarket sound systems and gauges are another prime target for thieves.

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It is arguable that a car alarm offers greater protection compared to an immobiliser. Unlike an immobiliser, an alarm serves to deter a thief from forcing entry into a car by attracting attention; it protects the both car and everything inside it. The only problem is this approach assumes that people who hear the alarm going off will take action – all too often they don’t.

“Bah, it’s just another false alarm,” they say to themselves...

Obviously, immobilisers and alarms have their own advantages and disadvantages. Thankfully, in today’s car security market, there’s generally no need to opt for one or the other – most high-quality security systems combine an immobiliser with an alarm.

And that’s great news.

Selecting a Security System

With the relatively cheap availability of combined immobilisers/alarms we strongly discourage anyone purchasing a system that addresses only one aspect of security. A combined system is the only way to go.

But where to from here?

Well, now we get into some of the technical stuff.

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Most off-the-shelf security systems come with a pair of remote control units for arming and disarming. In the majority of instances, these remote controls transmit a rolling code – this defeats any thief who retransmits the last signal from your remote.

And, in the event you forget to use the remote to arm the system, a good quality unit will automatically self-arm after a predetermined length of time. You can relax knowing that the system will never be left sitting unarmed.

So how does an alarm system know when the car is being tampered with, you ask?

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Well, the most basic input is derived from the door pin switches that are used to control the vehicle’s cabin lighting. In addition, many systems employ a motion or shock sensor. A motion sensor uses an active-type ultrasonic sensor that emits sound waves inside the cabin and detects when there’s a change in wave pattern. Another type of motion sensor uses a microwave sensor that relies on ultra-high frequency radio waves to detect movement – these are widely regarded as superior to ultrasonic motion sensors. Shock sensors generally use an ultrasonic sensor that is tuned to detect the frequencies produced by breaking glass and forced panel entry. These sensors usually have adjustable sensitivity to prevent false alarming when someone drives past with a big exhaust.

The majority of off-the-shelf security systems are fitted to your car using all-black wiring. This is desirable because it makes it very difficult for a thief to circumvent the system by tracing and cutting wires – they don’t know which one to cut.

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Another feature to look out for is a siren that incorporates its own battery back-up. A battery back-up siren will continue to scream even if a thief disconnects the vehicle’s battery terminals in an attempt to silence the system. Battery back-up sirens are quite common even in cheap security systems so there’s no reason not to have one.

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When it comes to immobilisers, there’s one simple rule – the more points of immobilisation the better. High quality systems provide two or three points of immobilisation, which are usually inserted into the fuel pump, starter motor or ignition circuit. We’ll make the point again – the more points of immobilisation, the better.

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At the premium end of the market some car alarm systems include a pager unit, which is integrated into the remote control unit. The pager typically vibrates and/or beeps whenever a break-in is detected, enabling the owner to spring into action.

This is a good idea but – still – one obvious flaw remains...

You’re stuffed if somebody steals your keys and remote.

Australian and New ZealandCar Security Standards

One of the safest ways to select a car security system is to keep an eye out for Australian and New Zealand standards approval.

The current standard for car alarms (AS/NZ 3749.1-2003) requires all-black wiring, a battery back-up siren and automatic self-arming. The alarm must also be professionally installed.

Immobilisers that meet AS/NZ 4601:1999 also require all-black wiring, automatic self-arming and must intercept at least two of the engine’s vital circuits. Again, professional installation is a prerequisite.

Note that Australian/New Zealand product certification is also important for insurance purposes. Many insurance companies give discounts only when your immobiliser or alarm meets the current AS/NZ standard.

Our Approach to Car Security

Recently, we were faced with the task of fitting a security system to our newly-acquired Nissan 180SX.

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Yes, we could have slapped down a large wad of money for the latest and greatest security system but we wanted to achieve a good all-round level of security with a budget of just AUD$250. Note that this budget also had to include the integration of remote control door locking/unlocking for the sake of added convenience.

Here’s how we did it...

Our System Configuration

To provide the maximum possible security we decided to employ two separate security systems – an off-the-shelf remote control immobiliser/alarm and a supplementary immobiliser circuit that only we know how to disarm.

Why did we take this two-pronged approach, you ask?

Well, this configuration gives us the convenience of remote operated alarm and door locking while also addressing the situation where a thief steals our remote/keys. Sure, they might be able to get into the car but they won’t be going anywhere...

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The remote control alarm/immobiliser we chose is the Full Feature Steel Mate Car Alarm, sold for AUD$199.00 through Jaycar Electronics (Cat No LA-9007). This unit comes with a pair of remote controls featuring rolling code transmission, an adjustable shock sensor, automatic self-arming, a battery back-up siren, immobiliser relay, a flashing LED and complete installation instructions. It can also be configured to operate central locking via the remote control.

The biggest negative of this system is the use of colour-coded wiring - this makes it easier for a thief to circumvent the system. However, as you’ll see in the final part of this series, the alarm wiring can still be very neatly integrated into the car’s existing wiring loom.

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In addition to the protection provided by the Steel Mate alarm/immobiliser, we also devised a custom supplementary immobiliser circuit. The circuit is automatically self-arming and only we know how to momentarily disarm it in order to start the engine.

Stick around - details of the supplemental immobiliser circuit will be covered in Part Two and we'll cover installation of the Steel Mate system in Part Three and Four.

Car Security Systems That We Considered

When configuring a car security system on a really tight budget you can’t go past the Do-It-Yourself kits available from electronics stores. We initially looked at the two car security kits sold by Jaycar Electronics – the Screecher MkII Alarm and MkII Immobiliser...

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At AUD$29.95, the Screecher MkII Car Alarm (Cat No KA-1813) employs an in-cabin mounted siren which is intended to make it unbearable for a thief to proceed and steal the car. The unit is armed and disarmed via a toggle switch that should be well hidden inside the cabin. An entry and exit delay and flashing ‘armed’ LED is also included.

Also retailing for AUD$29.95 is the Engine Immobiliser MkII (Cat No KC-5255). When armed, this unit enables the engine be started but cuts the ignition after about two seconds. The intention is to give the thief the impression that there is an intermittent problem. Again, this kit is armed and disarmed using a hidden toggle switch.

Both of these systems are great entry-level security measures but, in our case, neither suited the criteria – they can’t be easily or cheaply configured to work with remote control door locking.

At this point we began looking at off-the-shelf remote control systems...

The cheapest car security systems that incorporate a remote control door locking function are the Jaycar Shadow Immobiliser and Steel Mate Economy Car Alarm (Cat Nos LA-8970 and LA-9002 respectively).

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At AUD$129.50, the Shadow Immobiliser is very good value. It comes with a pair of code-hopping remote controls, automatic self-arming, all-black wiring and relays to provide two points of engine immobilisation. The unit meets current Australian and New Zealand4601:1999 standards.

Note that for an extra AUD$79.95, this unit can be upgraded to incorporate an alarm. The optional Alarm Upgrade Package (Cat No LA-8907) includes a shock sensor, bonnet pin switch and a battery back-up siren.

The basic Steel Mate Economy Car Alarm is another great buy at just AUD$119.00. It comes with a pair of non-code hopping remote controls, an adjustable shock sensor, immobiliser relay and a siren (without an internal back-up battery). Note that it does not meet AS/NZ standards.

Both of these systems were very attractive, but by the time you add the optional alarm upgrade to the Shadow Immobiliser its cost swells to almost AUD$210 - about AUD$10 dearer than the system we selected. We also didn’t like the quality of the supplied remote control units. The biggest problem with the Steel Mate Economy system was its lack of a battery back-up siren and non-code hopping remotes – it was worth the extra money to upgrade to the Full Feature version.

Note that we also investigated using a ‘brand name’ off-the-shelf security system. Our favourite was the Cyclops P385 alarm/immobiliser, which can be bought for just AUD$175. It has all the functions we wanted and meets Australian/New Zealand standards - but it had one major problem...

The local distributor wouldn’t provide us with the necessary detailed installation manual. These, we are told, are reserved for accredited car security workshops only; no good for a home installation!

Steal Stopping - Part Two
Steal Stopping - Part Three
Steal Stopping - Part Four

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