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Fig.1 Door Cylinder Lock Switch:

DOOR CYLINDER LOCK SWITCH
Vehicles manufactured for North American markets that are equipped with the optional Vehicle Theft Security System (VTSS) have a door cylinder lock switch secured to the back of the key lock cylinder inside the drivers front door. The door cylinder lock switch is a resistor multiplexed momentary switch that is hard wired in series between the door lock switch ground and right or left cylinder lock switch mux circuits of the Drivers Door Module (DDM) through the front door wire harness. The door cylinder lock switches are driven by the key lock cylinders and contain two internal resistors. One resistor value is used for the Lock position, and one for the Unlock position.

The door cylinder lock switches cannot be adjusted or repaired and, if faulty or damaged, they must be replaced.

The door cylinder lock switches are actuated by the key lock cylinder when the key is inserted in the lock cylinder and turned to the lock or unlock positions. The door cylinder lock switch close a circuit between the door lock switch ground circuit and the left or right cylinder lock switch mux circuits through one of two internal resistors for the Driver Door Module (DDM) when either front door key lock cylinder is in the Lock, or Unlock positions. The DDM reads the switch status through an internal pull-up, then uses this information as an input for the Vehicle Theft Security System (VTSS) operation.

The door cylinder lock switches and circuits can be diagnosed using conventional diagnostic tools and methods.

Fig.1 Hood Ajar Switch:

HOOD AJAR SWITCH
The hood ajar switch is a self-adjusting, normally closed, single pole, double throw momentary switch that is used only on vehicles built for sale in certain international markets where it is required equipment. The mounting bracket is fastened to the left inner fender. A molded plastic striker with three integral retainers is secured to the underside of the hood panel inner reinforcement to actuate the switch plunger as the hood panel is closed.The switch receives a path to ground through the left inner fender shield in the engine compartment.

The hood ajar switch adjusts itself as the striker pushes the switch body down through the switch when the hood panel is closed after the initial installation. This self-adjustment feature is only functional the first time the hood is closed following installation. If the switch requires adjustment following the initial installation, the switch must be replaced.

The normally closed hood ajar switch is normally held open when the hood panel is closed and latched. When the hood is opened, the switch plunger extends from the switch body and the switch contacts are closed. The hood ajar switch is connected in series between ground and the hood ajar switch sense input of the Body Control Module (BCM). The BCM uses an internal resistor pull up to monitor the state of the hood ajar switch contacts. The hood ajar switch can be diagnosed using conventional diagnostic tools and methods.

Fig.5 Intrusion Transceiver Module:

INTRUSION TRANSCEIVER MODULE (EXPORT ONLY)
An Intrusion Transceiver Module (ITM) is part of the premium version of the Vehicle Theft Alarm (VTA) in the Vehicle Theft Security System (VTSS). The premium version of the VTA is only available in vehicles built for certain markets, where the additional features offered by this system are required. The ITM is located in the passenger compartment. This unit is designed to provide interior motion detection, and serve as an interface between the Body Control Module (BCM) and the alarm siren module.

Premium VTSS also includes a battery-backed siren for the audible alert. In addition to the other features of the base VTSS, the ITM is used to monitor the interior of the vehicle for movement while the alarm is set. This feature can also be disabled with three additional lock commands from the Remote Keyless Entry system (which will be confirmed with an audible chirp) during the VTSS pre-arming sequence.

When the alarm is tripped it will actuate the hazard lamps for 25 seconds and the siren 28 seconds. After that period, if the disturbance is still present, only the siren will be activated again for 28 seconds with 5 second intervals between warning cycles. This will continue up to ten times unless the disturbance goes away. Also while the alarm is set the siren will monitor it's Fused B(+) and Siren Signal Control circuits. If either of these circuits become open the siren will trip itself to the alarming state.

NOTE:
- The intrusion transceiver module and/or siren must never be swapped from one vehicle to another. Once connected to a particular vehicle they will only properly function for that vehicle.
- If the VTSS indicator lamp comes ON after ignition ON and stays ON, the PCI bus communication with the powertrain control module possibly has been lost.

Fig.6 Intrusion Transceiver Module:

The ITM is concealed beneath a dedicated molded plastic trim cover that approximates the size and shape of a typical dome lamp housing. However, rather than a lens, the ITM features three sets of louvered openings. One set of louvered openings is located at each outboard end of the center rib, while the third set is centered. Each of the louvered openings is covered on the inside by a sight shield that extends the length of the center rib. The module is secured to a mounting bracket above the headliner.

Concealed within the housing is the circuitry of the ITM which includes a microprocessor, and an ultrasonic receive transducer. Both the transmit transducer on the right side of the module and the receive transducer on the ITM circuit board are aimed through two small round holes in the sight shield of the trim cover. The ITM is connected to the vehicle electrical system by a take out and connector of the overhead wire harness that is integral to the headliner.

The ITM unit cannot be adjusted or repaired and, if faulty or damaged, it must be replaced. The ITM is serviced as a unit with the trim cover.

The microprocessor in the Intrusion Transceiver Module (ITM) contains the motion sensor logic circuits and controls all of the features of the premium version of the Vehicle Theft Alarm (VTA). The ITM uses On-Board Diagnostics (OBD) and can communicate with other modules in the vehicle as well as with the DRB III scan tool using the Programmable Communications Interface (PCI) data bus network. This method of communication is used by the ITM to communicate with the Body Control Module (BCM) and for diagnosis and testing. The ITM also communicates with the alarm siren over a dedicated serial bus circuit.

The ITM microprocessor continuously monitors inputs from its on-board motion sensor as well as inputs from the BCM and the alarm siren module. The ITM motion sensor transmits ultrasonic signals into the vehicle cabin through a transmit transducer, then listens to the returning signals as the bounce off of objects in the vehicle interior. If an object is moving in the interior, a detection circuit in the ITM senses this movement through the modulation of the returning ultrasonic signals that occurs due to the Doppler effect. The motion detect function of the ITM can be disabled by depressing the "Lock" button on the Remote Keyless Entry (RKE) transmitter three times within 15 seconds, while the security indicator is still flashing rapidly or by cycling the key in the driver door cylinder from the center to the lock position. The ITM will signal the alarm siren module to provide a single siren "chirp" as an audible confirmation that the motion sensor function has been disabled.

If movement is detected, the ITM sends an message to the BCM over the PCI data bus to flash the exterior lighting and send a message to the alarm siren module over a dedicated serial bus line to sound the siren. When the BCM detects a breach in the perimeter protection through a door, tailgate, flip-up glass, or hood ajar switch input, it sends an message to the ITM and the ITM sends an message to the BCM over the PCI data bus to flash the exterior lighting and send a message to the alarm siren module over a dedicated serial bus line to sound the siren. The ITM also monitors inputs from the alarm siren module for siren battery or siren input/output circuit tamper alerts, and 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 ITM. If a fault does not reoccur for fifty ignition cycles, the ITM will automatically erase the stored DTC.

The ITM is connected to the vehicle electrical system through the overhead wire harness. The ITM receives battery voltage on a B(+) circuit through a fuse in the Junction Block (JB), and is grounded to the chassis at G303. These connections allow the ITM to remain operational, regardless of the ignition switch position. The hard wired inputs and outputs for the ITM may be diagnosed and tested using conventional diagnostic tools and procedures. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the ITM, the PCI data bus network, or the electronic message inputs to and outputs from the ITM. The most reliable, efficient, and accurate means to diagnose the ITM, the PCI data bus network, and the message inputs to and outputs from the ITM requires the use of a DRB III scan tool. Refer to the appropriate diagnostic information.