Circuit Description
The Passlock™ system is provided in order to prevent vehicle theft if
the ignition lock cylinder is forced to rotate. The Passlock controller reads the
coded Passlock™ data signal. The data consists of a voltage generated by a voltage
divider network created between the Passlock assembly and the Passlock™ controller.
If the data is correct , indicating rotation of the lock cylinder with the proper
mechanically cut key, then the Passlock™ controller sends a password to the
Powertrain controller over the class 2 bus to indicate that starter engagement
should be allowed. The Passlock™ controller also interfaces with the driver
displays subsystem to indicate, via a Security telltale, the Passlock™
subsystem's status and acute subsystem failures.
The components of the Passlock™ System are as follows:
• | The body control module (BCM) |
• | The security indicator on the instrument cluster |
• | The engine control module (ECM) |
Ignition Switch
The ignition switch contains the wiring and electrical switching portion of
the column mounted ignition assembly. The ignition switch includes wiring pigtails
which connect it to the base of column connector, the Passlock™ Sensor is
an internal resistor inside the ignition switch.
Body Control Module (BCM)
The BCM contains the logic of the theft deterrent system. The BCM provides
the battery positive voltage to operate the Passlock™ Sensor. The BCM also
measures the voltage of the security sensor signal circuit. The voltage measured
will indicate whether the Passlock™ Sensor has been activated and whether the
resistance value from the sensor is a valid value or the tamper value. If voltage
measured is in the valid range, the BCM compares this voltage, voltage code, to
a previously learned voltage code. If the voltage codes match, the BCM sends a class 2
message containing a password to the ECM. If the voltage codes do not match, or the
voltage is in the Tamper range, or there is a circuit fault, the BCM will not send
the correct password to the ECM, and the vehicle will not start.
Engine Control Module
The engine control module (ECM) contains the remainder of the logic of the
theft deterrent system. If a class 2 message containing a valid password
is received from the BCM, the ECM will allow starter engagement. If the ECM does
not receive a class 2 message, or receives a class 2 message with an incorrect
password, the engine will not crank.
Theft System Indicator
The IPC illuminates the theft deterrent indicator as determined by the
theft deterrent system. The IPC receives a class 2 message from the
BCM requesting illumination.
• | The vehicle theft deterrent (VTD) system requests the IPC to illuminate
the indicator only when the ignition switch is ON. |
• | The content theft deterrent (CTD) system requests the IPC to illuminate
the indicator only when the ignition switch is in the OFF or ACC positions
or during RAP. |
• | The body control module performs the displays test at the start
of each ignition cycle. The indicator illuminates for approximately 3 seconds. |
Fuel Lockout Cycle
When it receives a password which is incorrect or a password which indicates
tamper and the ECM disables the starter, the starter remain disabled for 10 minutes
even if the ignition switch is turned from the RUN position to the OFF position.
Changing the Passlock™ Components
The following components contain codes or passwords, or must learn codes or
passwords for the Passlock™ system to allow the vehicle to start:
If any of these parts are replaced, a learn procedure must be performed. Refer
to
Programming Theft Deterrent System Components
. If parts are replaced and a learn procedure is not performed, the engine will
not crank.