In Part Three of this series we began the Do-It-Yourself installation of an
off-the-shelf remote control alarm/immobiliser. Now, in the final part, it’s
time to finish the job.
Do-It-Yourself Security System
Mounting the Shock Sensor
The Steel Mate plug-in shock sensor has a pair of mounting tabs that enable
it to be screwed into place. The instructions suggest that the shock sensor be
mounted to part of the vehicle’s body frame – somewhere the sensor will detect
the shock of a break-in.
In the case of our 180SX, we firmly cable-tied the shock sensor to a
structural beam under the dashboard. We tested its response by striking the
radiator support panel with the handle of a screwdriver to replicate a break-in
and, sure enough, the shock sensor triggered the siren.
If the shock sensor does not respond you can alter its sensitivity using an
adjustment screw on the sensor body. This adjustment screw can also be used to
desensitise the shock sensor if you later have problems with false-alarming.
Fitting the Immobiliser Relay
The Steel Mate alarm comes with a normally-open relay which can be employed
to disable the starter, ignition or electric fuel pump. The relay is rated up to
30 amps, which is enough to cope with any of these devices.
When engine immobilisation is required (such as when the alarm is armed or
the anti-hijacking mode is triggered) the alarm module disconnects earth from
the coil side of the relay. This causes the switch side of the relay to go
open-circuit, cutting power to your chosen point of immobilisation.
The coil side of the relay uses a white and yellow wire, while the switched
side uses a pair of large diameter green wires.
We selected the ignition system as the point of immobilisation in our 180SX.
Using a factory wiring diagram, we located the wire between the vehicle’s ECU
and ignition coil relay (which provides power to each direct-fire coil). This
wire was then cut and the switched side of the immobiliser relay was soldered to
This leaves the white and yellow wire from the coil side of the immobiliser
The white wire is connected to Accessories and the yellow wire connects to
the immobilisation control wire (yellow) from the alarm module. The alarm uses
the immobilisation control wire to disconnect earth from the coil, which opens
the switched side of the relay and immobilises the engine.
Once the immobiliser relay is fitted and the alarm is armed, the engine can
be cranked over via the ignition but it refuses to fire into life; exactly what
Integration of Central
Our Nissan 180SX is factory fitted with a basic key-operated central locking
arrangement – a system that comprises a lock position switch inside the driver’s
door and a motor-driven slave actuator in the passenger door. Whenever the
driver’s door is manually locked or unlocked, the lock position switch sends the
appropriate signal to the slave actuator in the passenger door.
From the outset of this project we made the decision to upgrade to remote
control door locking/unlocking via the alarm system. However, to enable fully
remote control locking/unlocking of both doors, a motor-driven master actuator
must be added inside the driver’s door.
We employed a new Jaycar master actuator which retails for just AUD$11.95.
The master actuator kit (Cat. No. LR-8816) is supplied with mounting hardware
and a basic installation manual.
Fitment of the master actuator requires removal of the driver’s door trim and
weather shield. Once these are removed, you should be able to identify a metal
rod inside the door that moves as you lock/unlock the door. This is the locking
rod that must be connected to the new master actuator.
Find a position inside the door where there’s enough space to mount the
actuator so that its push/pull axis is parallel with the locking rod. It is
essential that the actuator is mounted on the same axis as the locking rod. Once
you’ve found a position, don’t forget to check that the actuator has adequate
clearance for the window mechanism.
The actuator is mounted to the inner skin of the door using the supplied
support band. Unfortunately, the support band was too short in this instance so
we made a small extension tab from scrap metal. One end of the mounting band was
secured using an existing hole in the door while the opposite end required
drilling a dedicated hole. Both ends were screwed into place using short
self-tapping screws – you don’t want a long self-tapper scratching the door
glass as is slides up and down...
The new actuator can now be connected to the vehicle’s locking rod using the
supplied control rod and fixing block.
Manoeuvre the supplied control rod through the eye in the end of the actuator
piston. The control rod should now be bent so that it aligns closely with the
vehicle’s locking rod. This photo shows the bends we made in the control rod for
our 180SX. Cut off any excess – we used only a very short control rod.
Once the control rod is bent and cut to suit, it can be connected to the
vehicle’s locking rod using the fixing block. The fixing block comprises two
parallel passages which fit over each rod. There are four screws in the block
that, when tightened, clamp down on each rod and links their movement together.
Note that this can be a fiddly job – we suggest screwing one side of the fixing
block onto the door rod first and securing the control rod second.
Important - the actuator should be set mid-way through its travel when linked
to the vehicle’s locking rod.
This photo shows what our installed master actuator looks like.
Now comes the central locking wiring.
The master actuator has five wires attached. Forget about the black, red and
white wires – the only ones we need to use are the blue and green wires.
In most instances you’ll need a length of extension wire to join the
actuator’s wires to the alarm module. Solder the actuator’s blue and green wires
to the extension wire and route it parallel with the existing door loom (where
fitted). Wherever possible, it’s also desirable to route the wire through a
factory rubber jacket in the doorjamb.
With the master actuator’s extension wires now accessible near the driver’s
kick panel, connect them to the switched door lock outputs from the alarm module
(white and white/black wires).
Next, connect the alarm module’s normally-closed door lock outputs (orange
and orange/black wires) to earth. The normally-open door lock outputs (yellow
and yellow/black wires) should then be connected to permanent 12V.
Tip - these can be spliced into the alarm module’s existing 12V and earth
At this stage you need to check the orientation of the actuator’s blue and
Press the ‘lock’ button on one of the remote control units and the doors
should lock at the same moment the alarm is armed. If the actuator’s wires are
incorrectly oriented the doors will unlock when the alarm is armed or vice
versa. If this happens, you need to swap the orientation of actuator’s blue and
green wires with relation to the alarm’s switched door lock outputs (white and
white/black wires). Solder them together once finalised.
And that’s the central locking part of the job done. If your car requires a
different central locking configuration to that described here, the necessary
wiring details are outlined in the alarm’s installation manual.
Route the alarm’s flashing LED through the dashboard and decide on a place to
mount it. The LED should be mounted somewhere prominent; we chose the top of the
steering column trim.
If you follow in our footsteps you’ll need to drill a 6.5mm hole through the
column trim (being careful not to scuff the visible surface). Once the hole is
drilled you can push the flashing LED through from the bottom. Unfortunately, a
LED clip is not supplied so we purchased a 5mm clip from Jaycar for a neater
finish. A pack of 20 LED clips (Cat. No. HP-1102) costs AUD$2.50 – they aren’t
In these closing stages you should revise the path of all alarm-related wires
- make sure none are pulled tight, there are no fouling issues and try to keep
them as hidden as possible. If there’s adequate space under the dashboard you
may be able to conceal the coloured alarm wires in split convoluted tubing –
this camouflages them as part of the vehicle’s original wiring loom.
Use the supplied keys to switch the under-bonnet siren to battery back-up
mode, refit all interior trim, familiarise yourself with the user’s manual and
Congratulations - your car is now secure and you haven’t spent a bomb!