Intrusion Module - Operation

OPERATION

The microprocessor in the intrusion module contains the motion detection logic circuits and controls all of the features of the premium version of the Vehicle Theft Alarm (VTA). The module uses On-Board Diagnostics (OBD) and can communicate with other modules in the vehicle as well as with a diagnostic scan tool using the Controller Area Network (CAN) data bus. This method of communication is used by the module to communicate with the Totally Integrated Power Module (TIPM) and for diagnosis and testing through the 16-way data link connector located on the driver side lower edge of the instrument panel. The intrusion module also communicates with the alarm siren over a dedicated serial bus circuit.

The intrusion module microprocessor continuously monitors inputs from the intrusion sensor transmitter and receiver as well as inputs from the TIPM and the alarm siren module. The module energizes the intrusion sensor transmitter, which transmits ultrasonic signals into the vehicle cabin through a transmit transducer, then monitors the current draw of the transmitter to detect problems with the transmitter and transmitter circuits. The module also energizes the intrusion sensor receiver, which listens to the ultrasonic signals through a receive transducer as they bounce off of objects in the vehicle interior, then monitors the current draw of the receiver for data signals and to detect problems with the receiver and receiver circuits. If an object is moving in the interior, a detection circuit in the module senses this movement through the modulation of the returning data signals from the receiver.

If movement is detected while the VTA is armed, the intrusion module sends an electronic status message to the TIPM over the CAN data bus to flash the exterior lighting, and sends an electronic message to the alarm siren module over a dedicated serial bus line to sound the siren. When the TIPM detects a breach in the perimeter protection through a door, liftgate or hood ajar switch input, it flashes the exterior lighting and sends an electronic message to the intrusion module and the module sends an electronic message to the alarm siren module over a dedicated serial bus line to sound the siren.

The module also monitors message inputs from the alarm 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. An active fault only remains for the current ignition switch cycle, while a stored fault causes a DTC to be stored in memory by the intrusion module. If a fault does not recur for 50 ignition cycles, the module will automatically erase the stored DTC.

The intrusion module is connected to the vehicle electrical system through the body wire harness. The module receives battery current through a fuse in the TIPM, and receives ground through the body wire harness. These connections allow the module to remain operational, regardless of the ignition switch position.

The hard wired circuits of the intrusion module may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the intrusion module or the electronic controls or communication between modules and other devices that provide some features of the VTA. The most reliable, efficient, and accurate means to diagnose the intrusion module or the electronic controls and communication related to intrusion module operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.