Shopping: Real Estate |  Costumes  |  Guitars
This Issue Archived Articles Blog About Us Contact Us
SEARCH


Steal Stopping - Part Two

Installing a stand-alone supplementary immobiliser.

By Michael Knowling

Click on pics to view larger images

At a glance...

  • Second part of four part series
  • Step-by-step installation of a stand-alone supplementary immobiliser
  • Total cost under AUD$20
Email a friend     Print article

In the first part of this series we devised how we going to secure our Nissan 180SX for a total cost of under AUD$250. Now it’s time to get stuck into the install.

We’ll begin with the stand-alone supplementary immobiliser - something which can be added to any car, regardless of whether a security system is already fitted.

Necessary Components

Click for larger image

A supplementary immobiliser can be a very simple system comprising just a handful of components. Our installation required only a relay, momentary pushbutton switch, some terminals and hook-up wire.

The total cost for components was around AUD$20.

Installation

Point of Immobilisation

There are three common points of immobilisation – the ignition, starter motor and fuel pump. Wherever possible, it’s best to choose a point of immobilisation that a thief would find inaccessible. Note that it’s pointless to immobilise the starter motor in a vehicle fitted with a manual gearbox – the car can be simply push-started...

Click for larger image

In the case of our 180SX we chose the starter wire of the ignition circuit as the point of immobilisation. A diagram is useful for finding the appropriate wire, but you can’t go past a multi-meter. The starter wire of our car showed 0V, except when being cranked when it showed around 11V.

Once you’ve identified the correct wire, back-track it through the vehicle’s wiring loom - the immobilisation circuit should be buried as far into the car’s wiring loom as possible. Cut the appropriate wire and solder a length of hook-up wire to each exposed end. These hook-up wires will connect to the immobilisation relay. Note that the hook-up wire should be the same gauge as the wire that you’ve cut.

Click for larger image

The relay we used is a conventional normally-open automotive relay that’s rated at 30 amps. A thirty amp current rating is ample for this application. Hide the relay under the dash where it’s inaccessible for a thief and connect the hook-up wires from the ignition circuit.

Click for larger image

The wires from the ignition circuit must connect to the switched output section of the relay. We used insulated crimp terminals to connect each wire to the relay.

There are two more wires to connect to the immobilisation relay. An earth (anywhere convenient on the metalwork of the car is fine) and the input for arming/disarming.

Arming/Disarming

The arming/disarming circuit serves to energise the relay when you want to start the vehicle. The circuit can be anything from a simple hidden switch to a more elaborate arrangement, as used here.

Click for larger image

The approach we took with our 180SX incorporates two separate switches that must be closed simultaneously for the vehicle to start. Furthermore, the use of momentary, normally-open switches means the immobiliser is effectively self-arming – it doesn’t require separate switching on/switching off.

The switches to arm/disarm the immobiliser can be dedicated switches hidden throughout the cabin or – more daringly – you might decide to make use of a factory switch.

Click for larger image

The two arming/disarming switches should be wired in series. This means both switches must be closed simultaneously to energise the immobilisation relay. Connect the arming/disarming switch circuit to the immobiliser relay. Note that, like most good security systems, we used all-black wiring for the entire immobilisation circuit.

Now for the moment of truth.

Try starting the car with the immobiliser switch(es) closed. If the circuit is correctly oriented, the car should start as normally. You will hear the immobilisation relay click into action. Now try starting the car without touching any of the switches. If you hear nothing, congratulations - you have completed your stand-alone supplemental immobiliser.

In the third and fourth (final) parts of this series we'll take you through the installation of an off-the-shelf remote control security system.

Did you enjoy this article?

Please consider supporting AutoSpeed with a small contribution. More Info...


Share this Article: 

More of our most popular articles.
A brilliant do-it-yourself handheld spotlight or bike headlight

DIY Tech Features - 11 February, 2008

Building a High Performance LED Lighting System, Part 1

A custom PowerChip remap - now she comes alive!

DIY Tech Features - 8 March, 2011

Powering-Up the 1.9 litre TDI, Part 4

An incredible way of producing your own vehicle

DIY Tech Features - 3 February, 2009

Building an Ultra Light-Weight Car, Part 1

Electricals

DIY Tech Features - 3 April, 2012

A New Home Workshop, Part 7

The steering

DIY Tech Features - 2 June, 2009

Chalky, Part 4

Finding the best location for engine bay vents

DIY Tech Features - 10 June, 2004

Undertrays, Spoilers & Bonnet Vents, Part 3

Beginners' guide to slipping through the air easily

Technical Features - 8 March, 2008

Low Drag Car Aerodynamics

Form beads in aluminium, steel and stainless steel intercooler plumbing

DIY Tech Features - 11 February, 2014

Make your own tube beader

Restoring a petrol bowser on the cheap!

Special Features - 25 November, 2008

Restoring a Petrol Bowser

Understanding circuits

DIY Tech Features - 9 December, 2008

How to Electronically Modify Your Car, Part 2

Copyright © 1996-2020 Web Publications Pty Limited. All Rights ReservedRSS|Privacy policy|Advertise
Consulting Services: Magento Experts|Technologies : Magento Extensions|ReadytoShip