Vehicle Theft Alarm: Notes

The Electromechanical Instrument Cluster (EMIC) is used on this vehicle to control and integrate many of the functions and features included in the Vehicle Theft Alarm (VTA). The EMIC is also sometimes referred to as the Cab Compartment Node (CCN). In the VTA system, the EMIC receives inputs indicating the status of the door ajar switches, the ignition switch, the liftgate ajar switch, the flip-up glass ajar switch, and the power lock switches. In vehicles built for certain export markets where it is required, the hood ajar switch provides a hard wired input to the Front Control Module (FCM) and both the FCM and the intrusion module provide electronic message inputs to the EMIC over the Controller Area Network (CAN) data bus. The EMIC processes the information from all of these inputs, internally controls the security indicator as appropriate, and sends electronic messages to the FCM over the CAN 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. On vehicles with an intrusion module, the horn output of the FCM is replaced by an output of the siren module that is controlled by the intrusion module.

The hard wired circuits between components related to the VTA system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the VTA system or the electronic controls or communication between modules and devices that provide some features of the VTA system. The most reliable, efficient, and accurate means to diagnose the VTA system or the electronic controls and communication related to VTA system operation requires the use of a diagnostic scan tool. See the VEHICLE THEFT SECURITY SYSTEM menu item on the scan tool. Refer to the appropriate diagnostic information.

Following are paragraphs that briefly describe the operation of each of the VTA features. See the owner's manual in the vehicle glove box for more information on the features, use and operation of the VTA.