Operation (page 3 of 3)

The energised alarm relay (C0731-5) also provides a feed to fuse 20 of the passenger compartment fuse box (C0581-20) on an orange/red wire. Fuse 20 (C0581-19) then supplies a feed to the LH (C0003-2) and RH horns (C0004-2) on purple/black wire.

By switching the earth path on and off, the alarm ECU can control the operation of the sounder and the horns.

The alarm ECU (C0057-4) supplies a feed to the anti-theft alarm LED (C1060-3) on a pink wire. Because the potential difference across the LED is 0 volts, the LED fails to illuminate.

To illuminate the LED, the alarm ECU (C0057-4) withdraws the feed on the pink wire, and provides a path to earth. Current can now flow and illuminate the LED. The alarm ECU can control the flashing sequence of the LED by switching the feed/earth on the pink wire.

Depending on market, some vehicles are also fitted with a BBUS. The BBUS has its own internal power supply. Should the vehicle battery or the sounder be₁ disconnected, the BBUS will sound for approximately 4 /₂ minutes. To disconnect the vehicle battery without sounding the alarm See Repair Manual, Maintenance, Battery Condition.

The BBUS (C0666-2) is supplied constant battery voltage from fusible link 5 (C0570-2). The BBUS (C0666-4) is earthed via earth header 550. A battery voltage signal is also supplied to the BBUS (C0666-3) from the alarm ECU (C0057-5). When the alarm is triggered, the alarm ECU withdraws this feed, and the BBUS sounds.

The BBUS (C0666-1) also receives an ignition feed from fuse 1 of the passenger compartment fuse box (C0580-2) on a white/green then black wire. All connections to and from the BBUS are on black wires.

The alarm ECU also controls the operation of the interior lamps. See Interior Lamps.