The Perimetric Alarm

The Perimetric Alarm

The perimetric alarm can only be set using the handset. Each door, the bonnet and the luggage compartment incorporates a switch that closes as the aperture is opened. When a switch is closed, an earth signal is sent to the alarm ECU on the P/W wire for the driver and passenger doors, on a P/K wire for the boot and on a P/R wire for the bonnet.

If a door is opened when the alarm is armed, the alarm ECU sends an earth on the P/B wire to one side of the horn relay coil. Since the other side of the coil receives battery voltage on the P wire from fuse B6 in passenger compartment fuse box, the relay will energise causing the horn to sound. Once triggered, the horn will sound for a period of approximately 30 seconds - it can be silenced by pressing the plain button on the handset.

Engine Immobilisation

The engine is immobilised when the perimetric alarm is set, inhibiting the engine primary electrical circuits. Immobilisation is removed when the LH handset button is pressed. The alarm ECU provides an earth on the W/R wire (via the automatic inhibitor switch on the W/ LG wire in the case of vehicles fitted with automatic gearbox) to one side of the starter relay coil. Since the other side of the coil is receiving battery voltage from fuse C8 the passenger compartment fuse box on the W/R-W/K wire, the relay is energised. Once this occurs, battery voltage is switched from link 4 in the engine compartment fuse box on the N wire via the MEMS relay module to the starter motor on the N/R wire, with an immobilisation signal being sent to the MEMS ECM on the W/S wire.

Passive Engine Immobilisation

Even if the car is not locked, the passive immobilisation feature will be enabled approximately 30 seconds after ignition is switched OFF and the driver's door has been opened. This state is indicated by the anti-theft alarm indicator flashing. While the door is open, the anti-theft alarm indicator illuminates continuously.

In this condition, the engine can be re-mobilised by pressing the LH button on the handset before operating the starter switch.

Handset Battery Replacement

Dependent on usage, the CR2032 type battery in the handset should last for three years. When the battery is near the end of its life, a reduction in the operating range of the handset may be noticed. To change the battery, first carefully prise open the handset casing at the key ring end, taking care not to damage the seal. Slide the battery out, without bending the clip or touching any of the contact surfaces. Press and hold each handset button for five seconds, to allow residual power to discharge.

Without touching the contact surfaces, carefully slide a new battery into the clip, ensuring that the side marked '+' faces the clip. Snap together the two halves of the handset case.

Unlock the car then operate the RH (lock symbol) button at least four times, to resynchronise the handset to the car. The handset is now ready for use.