The vehicle theft deterrent system is designed in order
to prevent vehicle theft by disabling the fuel injectors unless the lock cylinder
is engaged by the correct mechanical key. The theft deterrent system
uses the following 4 components for theft prevention:
| • | The body control module (BCM) |
| • | The powertrain control module (PCM) |
When starting the engine, the PCM searches for a password from the BCM
through the Class 2 serial data circuit. If the password is not recognized
or not present, the PCM will disable the fuel injectors. Two modes of
tamper detection are provided:
| | The engine will start and stall quickly. SECURITY telltale will flash
on the instrument panel cluster (IPC) and then stay ON steady. |
| • | Incorrect or disable password received (More than 3 invalid
passwords are received) |
| | The engine is disabled for at least 10 minutes and the SECURITY
telltale will illuminate solid on the IPC during the 10 minutes. |
After the vehicle has passed theft detection, the PCM will continue
normal operation.
Ignition Switch
The mechanical key and lock cylinder is located on the steering column.
The main electrical switching portion of the assembly is separate from
the key and lock cylinder. The VTD portion of the ignition switch is the
Passlock™ cylinder.
The Passlock™ lock cylinder is a locking cylinder that turns a
magnet past a stationary hall effect sensor. When turned to crank, the hall
effect sensor is latched which applies a fixed resistance to the Passlock™
signal data circuit. The voltage measured by the BCM on the Passlock™
signal data circuit is the Passlock™ data value.
Body Control Module (BCM)
The BCM compares the Passlock™ data value to a value that it has
stored in memory. If the values match the BCM sends a password via the class
2 serial data line to the PCM.
Powertrain Control Module (PCM)
When the PCM receives the correct password, the PCM enables the fuel
injection system, allowing the vehicle to operate correctly. The PCM
may allow the car to start and quickly stall during a failed theft
condition.
If the BCM does not receive a Passlock™ data value, the BCM will
enter a short tamper mode. During this mode, the VTD system will not
allow the car to operate for 4 seconds.
If the Passlock™ data value is incorrect, the VTD system will
enter the long tamper mode. In the long tamper mode, the following actions
will occur:
| • | The THEFT SYSTEM indicator will flash. |
| • | The fuel injectors will be shut off for approximately 10 minutes. |
Although the vehicle may start, the engine will quickly stall due to
a fuel cut-off.
In the event of an open in the serial data communication between the
BCM and the PCM or a failure in the Passlock™ lock cylinder, the following
actions occur:
| • | The VTD system will become fail-enabled if the car has already
passed theft for that ignition cycle (i.e. the engine is running). |
| • | The PCM or the BCM may set diagnostic trouble codes
(DTCs). |
| • | The THEFT SYSTEM indicator will light continuously. |
| • | The PCM will become fail-enabled for future ignition cycles. |
If a failure occurs when the ignition is off, while the VTD system
is not fail-enabled, the PCM will never receive a valid password, and will
not allow vehicle operation by disabling the fuel injectors.
