Security Lamp/Indicator: Description and Operation

A security indicator is standard equipment on all instrument clusters. However, on vehicles not equipped with the optional Vehicle Theft Security System (VTSS), this indicator is mechanically disabled. The security indicator is located in the Information Center area of the instrument cluster, to the left of center. The security indicator consists of a stencil-like cutout of the word "SECURITY" in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the indicator from being clearly visible when it is not illuminated. A red Light Emitting Diode (LED) behind the cutout in the opaque layer of the overlay causes the "SECURITY" text to appear in red through the translucent outer layer of the overlay when it is illuminated from behind by the LED, which is soldered onto the instrument cluster electronic circuit board. The security indicator is serviced as a unit with the instrument cluster.

The security indicator gives an indication to the vehicle operator when the Vehicle Theft Security System (VTSS) is arming or is armed. On models equipped with the Sentry Key Immobilizer System (SKIS), the security indicator also gives an indication to the vehicle operator of the status of the SKIS. This indicator is controlled by a hard wired input to the instrument cluster from the Central Timer Module (CTM) on the VTSS indicator driver circuit and, if the vehicle is so equipped, by a transistor on the instrument cluster circuit board based upon electronic messages received by the cluster from the Sentry Key Immobilizer Module (SKIM) over the Programmable Communications Interface (PCI) data bus. The security indicator Light Emitting Diode (LED) receives battery current on the instrument cluster electronic circuit board at all times through the fused B(+) circuit. Therefore, the LED can be illuminated regardless of the ignition switch position. The LED only illuminates when it is provided a path to ground by the CTM or by the instrument cluster transistor. The security indicator will be illuminated for the following reasons:

- Bulb Test - Each time the ignition switch is turned to the On position, the SKIM tells the cluster to illuminate the SKIS indicator for about three seconds as a bulb test. There is no bulb test performed on this indicator for models that are not equipped with the optional SKIS.

- VTSS Indication - During the sixteen second VTSS arming function, the CTM will flash the security indicator on and off repeatedly at a steady, fast rate to indicate that the VTSS is in the process of arming. Following successful VTSS arming, the CTM flashes the security indicator on and off continuously at a slower rate to indicate that the VTSS is armed. The security indicator continues flashing at the slower rate until the VTSS is disarmed or triggered. If the VTSS has alarmed and rearmed, the CTM will flash the security indicator at a steady slow rate for about thirty seconds after the VTSS is disarmed.

- SKIM Lamp-On Message - Each time the cluster receives a lamp-on message from the SKIM, the security indicator will be illuminated. The indicator can be flashed on and off, or illuminated solid, as dictated by the SKIM message. The indicator remains illuminated solid or continues to flash until the cluster receives a lamp-off message from the SKIM, or until the ignition switch is turned to the Off position, whichever occurs first. For more information on the SKIS and the security indicator control parameters, (Refer to ELECTRICAL/VEHICLE THEFT SECURITY/SENTRY KEY IMMOBILIZER SYSTEM - OPERATION).

- Actuator Test - Each time the instrument cluster is put through the actuator test, the security indicator will be turned on, then off again during the bulb check portion of the test to confirm the functionality of the LED and the cluster control circuitry.

The CTM provides a hard wired ground input to the instrument cluster circuitry through the VTSS indicator driver circuit whenever the ignition switch is in the Off position and the VTSS is arming, armed, or triggered. When the ignition switch is turned to the On or Start positions, the SKIM performs a self- test to decide whether the system is in good operating condition. The SKIM then sends the proper lamp-on or lamp-off messages to the instrument cluster. For further diagnosis of the security indicator or the instrument cluster circuitry that controls the indicator, (Refer to ELECTRICAL/INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). If the instrument cluster flashes the SKIS indicator upon ignition On, or turns on the SKIS indicator solid after the bulb test, it indicates that a SKIS malfunction has occurred or that the SKIS is inoperative. The VTSS indicator driver circuit input to the instrument cluster may be diagnosed using conventional diagnostic tools and methods. For proper diagnosis of the VTSS, the CTM, the SKIS, the PCI data bus, or the electronic message inputs to the instrument cluster that control the security indicator, a DRBIII(R) scan tool is required. Refer to the appropriate diagnostic information.