So you think because your car has a remote control alarm, it’s secure,
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.
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
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.
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.
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
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
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.
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.
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.
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
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.
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
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
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.
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
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...
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
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).
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
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
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!