Installing a Key-Pad Immobiliser

Sure, you can fit a kill-switch. But where do you put it? Any place that you reckon is a good hiding spot is sure to have been thought of before - by thieves! Instead, what about installing a digital keypad immobiliser? Electronics and automotive accessory stores have these very cheaply, and installation will only take you a couple of easy hours.

We watched Leon Vincenzi of Awesome Automotive install a Jaycar Electronics keypad immobiliser.

To do the same you'll need:

• Hand tools: screwdriver, round file
• Electric drill, screws, washers
• Soldering iron, solder, wire
• Optional: multimeter

Most key-pad immobilisers consist of just the key pad, a wiring harness, instructions, and a heavy duty automotive relay. Oh yeah - and double-sided tape to hold the key-pad in place. This kit's got simple-to-follow instructions, so if you can read a circuit diagram, there's no problem in installing it.

First step is to find a place for the keypad. You can mount it on any flat, convenient surface inside the cabin, or you might want to place it out of sight inside the centre console storage bin. An advantage of keeping it hidden is that a potential thief isn't forewarned to its presence - but that also means that it doesn't scare thieves away!

Leon put the keypad next to the steering column. A blanking plate was carefully pried out with a screwdriver and then a file used to make a half-round hole for the cable. It's easy to break off bits of dash plastic (especially in older cars), so take care when removing trim pieces. With the blanking plate out, the other half of the hole was then filed and then the cable fed through.

It wouldn't look too good if the keypad fell off after a short while, so Leon first cleaned off any silicone coatings with a rag dampened with methylated spirits, before applying the double-sided tape and then the key-pad itself. Looks like it was always there, doesn't it! Okay, but what about the rest of the wiring?

The first decision in the wiring process is to decide on the circuit to be disabled. You can cut off the fuel pump, ignition coil, starter solenoid - or the injectors in an EFI car. Looking at the workshop manual will show you where these circuits are - Leon went for the injectors.

You want to make damn sure that the circuit that you're about to disable is the right one - Leon Vincenzi used a multimeter to trace the injector power supply wiring. If you don't have a multimeter, you can use the loom colour codes and a workshop manual to help you find your way. Having found the factory relay that supplied power to the injectors, Leon pulled the plug off and cranked the car. It didn't start, so he knew he'd found a good circuit to disable!

When the immobiliser's relay contact is open, no power can pass through it, disabling the circuit - so to wire in the new relay, an existing circuit needs to be cut. The instructions show all of this quite clearly. Soldering the wiring is a lot better than just wrapping the bared leads together, so Leon got out the iron. If you are using heat-shrink tubing over the joint (a good approach to take) make sure that you remember to slide the heat shrink on before you solder the wires!

The immobiliser relay should be mounted next to factory relays (or hidden altogether) so that it doesn't stand out like a new underbonnet addition. Why? 'Cos a new relay is an immediate guide to a thief as to the location of the immobiliser circuitry. Leon drilled a hole for a new self-tapping screw...

.... and then mounted the relay next to some other standard relays, partly hidden under factory wiring. The immobiliser relay is the one on the far right, concealed by the standard loom. Heatshrink was placed over the new wiring to conceal its foreign status and then the wires from the relay were fed into the cabin through a grommet in the firewall, allowing connection to the wires from the keypad. The immobiliser needs to be fed a constant 12 volts through an in-line fuse, it needs an earth (any convenient metal bolt attached to the chassis), and it needs a 12 volt ignition-switched voltage. All those connections can be made under the dash.

In only a few hours' work and your car can be like this one - considerably harder to steal!

Contact:

Jaycar Electronics www.jaycar.com.au

Awesome Automotive
+618 8277 3927

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