Security Alarm System Description - Ultrasonic System

Security Alarm System


The security alarm system is armed automatically after the doors, hood, and trunk or tailgate are closed and locked. The security indicator on the gauge assembly flashes after the system is armed.

The system is set off when any of these things occur.
  • A door is forced open
  • A door is unlocked without using the key or the transmitter
  • The trunk lid or tailgate is opened without using the key.
  • The hood is opened
  • The engine starter circuit and battery circuit are bypassed by breaking the ignition switch (KH, PH and KK models)

When the system is set off, the alarm sounds and the exterior lights (headlights, parking lights and taillights: FO model or turn signal lights: except (FO model) flash for 2 minutes (FO model) or 30 seconds (Except FO model) or until the system is disarmed by unlocking either door with the key or the transmitter.

For the system to arm, the ignition switch must be off and the key removed. Then, the security control unit must receive signals that the doors, hood, and trunk lid or tailgate are closed and locked. When everything is closed and locked, none of the control unit inputs are grounded.

The door switches, hood switch, trunk latch switch or tailgate latch switch, door lock knob switches, and door lock key cylinder switches are all open,. 10 seconds after the doors are locked with the key or the lock knob, or immediately after locking the doors with the remote transmitter, the system arms.

If anything is opened or improperly unlocked after the system is armed, the control unit gets a ground signal from that switch, and the system is set off.

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 get a ground signal, it thinks the vehicle is not closed and locked and will not arm.

An alarm that sounds for no apparent reason may have been set off by switch that is on the threshold of misadjustment. In this case, it may only take a significant change in outside temperature, the vibration of a passing truck, or someone bumping into the vehicle to make the alarm sound.

Ultrasonic System


KE model has the ultrasonic system. The system is constituted by the ultrasonic sensor and the alarm control siren that is a combined ACU and self powered siren.

The ultrasonic sensor uses the ultrasonic Doppler technology. It saturates the volume of the car with 40 kHz ultrasounds, convert the received signal that is generated by any moving target inside the volume into a rectangular wave characterized by the Doppler frequency, which is analysed by a dedicated algorithm, in-built the microcontroller.

The alarm control siren communicates with the ultrasonic sensor and the security control unit. If the alarm control siren receives an arm command from the security control unit, it enters the arm mode after default period time (stored in EEPROM memory) of 10 seconds.

If the alarm control siren receives alarm command from the ultrasonic sensor and the security control unit during arm condition, alarm control siren activates the internal siren.

The system has the power supply line ‘+B Tamper' function (cutting wire protection). If one or both power supply wires (+B, GND) are tampered during arm condition, the system changes to alarm mode. If the alarm condition remains, the alarm control siren will trigger in alarm 10 times (programmable in EEPROM memory).

The system has the serial line ‘alarm comm line tamper' function (not authorized disarm attempt). If wrong identification code is received by the ACU, the system changes to alarm mode. The alarm control siren will generate up to 10 alarm triggers for each arm cycle (programmable in EERPOM memory).

The system has the serial line ‘alarm comm line polling' function (connection monitoring). If this wire is interrupted during arm mode the system change to alarm condition. If the alarm condition remains, the alarm control siren will trigger in alarm 10 times (programmable in EEPROM memory).