PRE-RELEASE
Siren, anti-theft alarm (275)
| Siren, anti-theft alarm (275) |
| Location |
Siren, anti-theft alarm (275)
| Principal use |
Used by the anti-theft alarm to sound if the alarm is triggered.
| Type |
The siren incorporates a speaker, a rechargeable battery and a microprocessor. The internal battery is charged on command from the body control module (BCM) as soon as the ignition is turned to ON.
If the siren has been manipulated with in an armed state and has therefore self-activated, it will sound for 10x30 seconds with a 6 second interval between each period. The siren has varying tone ranging between 1800Hz and 3550Hz.
The siren has 7 normal operating modes:
| 1 | Disarmed & quiet | Anti-theft alarm disarmed. |
| 2 | Disarmed & Acoustic indicator | Remote control used on disarmed car.* |
| 3 | Armed & Acoustic indicator | Remote control used on armed car.* |
| 4 | Armed & Quiet | Car is alarmed. |
| 5 | Armed & Siren sounding | Car is alarmed and BCM has sent an alarm command. |
| 6 | Internal battery mode & Quiet | Car battery voltage has dropped slowly. |
| 7 | Internal battery mode & Siren sounding | Car battery voltage has dropped too quickly or communication with BCM broken. |
*Programmable function, also selectable using diagnostic tool.
| Connection |
The siren is continuously supplied with current and communicates with BCM via a 2-way communication cable. A command is sent from BCM to the siren to arm or disarm, alarm or provide an acoustic indication.
BCM sends data periodically so that the siren can detect a break in the communication cable. The siren sends the diagnostic status so that BCM knows it is in working order.
| Pin no. | Signal type | Description |
| 1 | - | Not used. |
| 2 | +30 | Power supply |
| 3 | Communication cable | Serial communication BCM - ASM. |
| 4 | Ground | Power supply |
Wiring diagram, power supply
