Description And Operation

DESCRIPTION 

Courtesy of CHRYSLER GROUP, LLC

An ultrasonic and anti-tilt security system uses ultrasonic waves to detect movement in the cabin when the vehicle alarm is activated. Should the vehicle be tilted when a wheel is removed or when towed, the vehicle's alarm will sound.

The alarm intervenes in the following instances:

• Perimeter protection - when a door, hood or the swing gate is opened illegally
• When the ignition system is started up outside of the vehicle's security system
• Cutting of the battery leads

The systems Intrusion Transceiver Module (ITM) (1) is battery-fed, the module and the anti-tilt sensor are packaged together and is located below the steering column.

OPERATION 

The ITM communicates with the siren module and the ultrasonic intrusion sensors over dedicated serial bus circuits.

The ITM continuously monitors inputs from the four microwave intrusion sensor transducers as well as inputs from the Body Control Module (BCM) and the siren module. The ITM energizes the intrusion sensors and anti-tilt sensor when the system is armed, then monitors inputs from the sensors related to motion and tilt detection as well as detecting problems with the sensors or sensor circuits. If an object is moving in the interior, a detection circuit in the intrusion sensor senses this movement through the modulation of the returning microwave signals that occurs due to the Doppler effect.

If movement is detected while the Vehicle Theft Alarm (VTA) is armed, the ITM sends an electronic status message to the BCM over the Controller Area Network (CAN) network data bus to flash the exterior lighting, and sends an electronic message to the siren module over a dedicated serial bus line to sound the siren. When the BCM detects a breach in the perimeter protection through a hardwired door, swing gate or hood ajar switch input, it sends an electronic message to the ITM and the ITM sends an electronic message to the siren over a dedicated Local Interior Network (LIN) bus communication circuit to sound the siren.

The ITM also monitors inputs from the siren module for siren battery or siren input/output circuit tamper alerts, and for siren battery condition alerts, then sets active and stored Diagnostic Trouble Codes (DTC) for any monitored system faults it detects.

Inputs

• Commanded ignition switch status from the BCM (CAN-IHS)
• Motion detection disable request from the BCM (CAN-IHS)
• VTA status from the BCM (CAN-IHS)
• System voltage from the BCM (CAN-IHS)
• Vehicle configuration parameter from the BCM (CAN-IHS)
• ITM ecu configuration from the BCM (CAN-IHS)
• "Heart Beat" command responses from the intrusion sensors
• Motion detection output from the intrusion sensors
• Tilt detection from the anti-tilt sensor
• Siren battery condition from the siren module

Outputs

• ITM alarm indicator request to the BCM (CAN-IHS)
• ITM motion detection disabled to the BCM(CAN-IHS)
• ITM status and alarm requests to the BCM (CAN-IHS)
• "Heart Beat" command signals to the intrusion sensors
• Siren battery management to the siren module