Antitheft and Alarm Systems: Description and Operation

The Vehicle Theft Security System (VTSS) is designed to provide perimeter protection against unauthorized use or tampering by monitoring the vehicle door ajar circuits, the driver side front door cylinder lock switch circuit, the power lock and unlock circuits, and the ignition switch circuit. If unauthorized use or tampering is detected, the system responds by pulsing the horn for up to about three minutes and flashing the hazard warning lamps for up to about eighteen minutes.

The VTSS includes the following major components.
- Door Cylinder Lock Switch (4) - A cylinder lock switch is located on the back of the lock cylinder on the driver side front door.
- Door Ajar Switches (5) - A door ajar switch is integral to the door latch mechanism of each front and rear door.
- Front Control Module (1) - The Front Control Module (FCM) is integral to the Integrated Power Module (IPM). The FCM/IPM is located in the engine compartment, near the battery and the Power Distribution Center (PDC).
- Horn Relay - The horn relay is located in the Power Distribution Center (PDC) in the engine compartment near the battery.
- Ignition Switch (3) - The ignition switch is located on the steering column in the passenger compartment.
- Instrument Cluster (2) - The ElectroMechanical Instrument Cluster (EMIC) is also known as the Cab Control Node (CCN) in this vehicle. The EMIC/CCN is located in the instrument panel above the steering column opening, directly in front of the driver.
- Security Indicator - The security indicator is integral to the instrument cluster.

Hard wired circuitry connects the VTSS components to the electrical system of the vehicle. These hard wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the VTSS components through the use of a combination of soldered splices, splice block connectors, and many different types of wire harness terminal connectors and insulators. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.

The ElectroMechanical Instrument Cluster (EMIC) is used on this model to control and integrate many of the functions and features included in the Vehicle Theft Security System (VTSS). In the VTSS, the EMIC receives inputs indicating the status of the door ajar switches, the door cylinder lock switch and the ignition switch. The EMIC will process the information from all of these inputs, internally control the security indicator as appropriate, and send electronic messages to the Front Control Module (FCM) over the Programmable Communications Interface (PCI) data bus. The FCM internally controls the output to the hazard warning lamps and sends a control output to energize or de-energize the horn relay as appropriate.

Following are paragraphs describing the operation of each of the VTSS features.

ENABLING
The EMIC must have the VTSS function electronically enabled in order for the VTSS to perform as designed. The logic in the EMIC keeps its VTSS function dormant until it is enabled using a diagnostic scan tool. The VTSS function of the EMIC is enabled on vehicles equipped with the VTSS option at the factory, but a service replacement EMIC must be VTSS-enabled by the dealer using a diagnostic scan tool.

ARMING
Passive arming of the VTSS occurs when the vehicle is exited with the key removed from the ignition switch, the headlamps are turned off, and the doors are locked while they are open using the power lock switch, or locked after they are closed by turning the driver side front door lock cylinder to the lock position using the key. Active arming occurs when the "Lock" button on the Remote Keyless Entry (RKE) transmitter is depressed to lock the vehicle. For active arming to occur, the doors must be closed and the ignition switch must be in the Off position when the RKE transmitter "Lock" button is depressed. The power lock switch will not function if the key is in the ignition switch or the headlamps are turned on with the driver side front door open.

Pre-arming of the VTSS is initiated when a door is open when the vehicle is locked using a power door lock switch or when the RKE transmitter "Lock" button is depressed. Pre-arming will not occur if the key is in the ignition switch or the headlamps are turned on with the driver side front door open. When the VTSS is pre-armed, the arming sequence is delayed until all of the doors have been closed. The VTSS will remain in "Pre-Armed" mode for up to seventeen seconds after all of the doors have been closed.

Once the VTSS begins the passive or active arming sequence, the security indicator in the instrument cluster will flash rapidly for about seventeen seconds. This indicates that VTSS arming is in progress. If the ignition switch is turned to the On position, a door is opened, a door is unlocked by any means, or the RKE "Panic" button is depressed during the seventeen second arming process, the security indicator will stop flashing and the arming process will abort. Once the seventeen second arming sequence is successfully completed, the security indicator will flash at a slower rate, indicating that the VTSS is armed.

DISARMING
Passive disarming of the VTSS occurs when the vehicle is unlocked using the key to unlock the driver side front door. If the vehicle is equipped with the optional Sentry Key Immobilizer System (SKIS), passive disarming will also occur by turning the ignition switch to the On position using a valid SKIS key. Active disarming of the VTSS occurs when the vehicle is unlocked by depressing the "Unlock" button of the RKE transmitter. Once the alarm has been activated, either disarming method will also deactivate the alarm. Depressing the "Panic" button on the RKE transmitter will not disarm the VTSS.

POWER-UP MODE
When the armed VTSS senses that the battery has been disconnected and reconnected, it enters its power-up mode. In the power-up mode the alarm system remains armed following a battery failure or disconnect. If the VTSS was armed prior to a battery disconnect or failure, the technician or vehicle operator will have to actively or passively disarm the alarm system after the battery is reconnected. The power-up mode will also apply if the battery goes dead while the system is armed, and battery jump-starting is attempted. The VTSS will be armed until the technician or vehicle operator has actively or passively disarmed the alarm system. If the VTSS is in the disarmed mode prior to a battery disconnect or failure, it will remain disarmed after the battery is reconnected or replaced, or if jump-starting is attempted.

TAMPER ALERT
The VTSS tamper alert feature will sound the horn three times upon disarming, if the alarm was triggered and has since timed-out (about eighteen minutes) or if the battery has been disconnected and reconnected. This feature alerts the vehicle operator that the VTSS alarm was activated while the vehicle was unattended.