Security Alarm System: Description of Operation
The security alarm system is armed automatically after the doors, hood, and trunk lid are closed and locked. For the system to arm, the ignition switch must be off, the key must be removed, and the security control unit must receive signals that the doors, hood, and trunk lid are closed and locked. The alarm can be disarmed at any time by unlocking either door with the key or the remote transmitter.
When everything is closed and locked, the only control unit inputs that are grounded, and have 0 volts , are the driver's door lock knob switch, and the audio unit. In other words, all of the other switches are open, including the key cylinder switches, and they have about 10 volts . Ten seconds after the doors are locked with the key or the lock knob (with the door open), or immediately after the doors are locked with the LOCK button on the remote transmitter, the security system arms, and the security indicator on the door panel flashes. If the security indicator does not flash, the system is not arming. Check the doors, hood, and trunk to see if they are closed. A beep to confirm the security alarm system is armed will sound if the LOCK button is pressed a second time within 5 seconds .
If one of the switches is misadjusted or there is a short in the system, the system will not arm. As long as the control unit continues to receive a ground signal, it senses that the vehicle is not closed and locked, and the system will not arm. Conversely, a switch that is slightly misadjusted can sound an alarm for no apparent reason. In this case, a significant change in outside temperature, the vibration of a passing truck, or someone bumping into the vehicle could cause the alarm to sound.
If anything is opened or improperly unlocked after the system is armed, the control unit receives a ground signal from that switch, and the 10 volts reference drops to 0 volts . If the radio is disconnected, the input loses its ground, and the input voltage goes to 10 volts . The system sounds the alarm when any of these things occur:
* A door is forced open
* A door is unlocked without using the key or the remote transmitter
* The hood is opened
* The trunk is opened without using the transmitter
* The audio unit is disconnected
* The panic mode is activated
When the system sounds the alarm, the security horn sounds and the exterior lights flash for 2 minutes . The alarm can be stopped at any time by unlocking either door with the key or by pushing any button on the remote transmitter.
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