The Passlock™ system is a vehicle theft deterrent system which deters
drive-away vehicle theft by disabling the engine operation if the ignition lock cylinder
is not rotated with the proper mechanically cut key.
The Passlock™ system is made up of an ignition lock assembly, Passlock™
sensor, body control module (BCM), instrument panel cluster (IPC), and either a powertrain
control module (PCM) for L61 engines, or an engine control module (ECM)
for L81 engines.
The ignition lock cylinder contains a magnet mounted on the lock cylinder and
a Passlock™ sensor assembly mounted on the ignition module which consists of
a security hall effect sensor, a tamper hall effect sensor, and output resistors.
A drill proof metal shield is also staked over the sensor housing.
The Passlock™ sensor mounted to the ignition lock cylinder assembly is
located inside the upper right side of the steering column. The Passlock™ sensor
contains 2 hall effect sensors: a tamper hall effect sensor and a security hall effect
sensor. The tamper hall effect sensor is mounted on top of the security hall effect
sensor. Should someone attempt to defeat the system by use of magnetic experimentation,
the tamper hall effect sensor will activate first.
The BCM has the Passlock™ controller integrated into it which controls
the majority of the security systems logic. The BCM reads the data from the Passlock™
sensor continuously. If the data is correct and has been received by the BCM within
a specified time, the BCM will send a coded password to the ECM/PCM. The ECM/PCM will
then allow the fuel injectors to operate.
The ECM is used on the L81 engine applications. The coded password for the security
system is sent from the BCM to the ECM via the controller area network (CAN) bus.
If the password is correct and received within the specified time, the ECM will allow
the fuel injectors to operate.
The PCM is used on L61 engine applications. The coded password for the security
system is sent form the BCM to the PCM via the class 2 data link. If
the password is correct and received within the specified time, the PCM will allow
the fuel injectors to operate.
The IPC contains the security telltale. The security telltale has 3 modes of
operation: Off, flashing, and on.
Security telltale will be off if:
| • | The ignition is in the OFF position. |
| • | The ignition is in the RUN, START, or ACC position and the security system
diagnostics have all passed. |
Security telltale will be on if:
| • | The BCM is performing a bulb check at vehicle start. |
| • | The security system diagnostics have not yet completed at vehicle start. |
| • | A security system diagnostic trouble code (DTC) is set in the BCM or ECM/PCM. |
Security telltale will be flashing if :
| • | The tamper hall effect sensor has been triggered. |
| • | The incorrect Passlock™ sensor data to the BCM for more than 5 seconds
during vehicle start. |
| • | No Passlock™ sensor data has been sent to the BCM for more than
5 seconds during vehicle start. |
| • | The security telltale will also flash when the content theft system is
in the armed mode. |
Security System Operation
The Passlock™ system is designed to prevent vehicle operation if the
mechanical key is not used to start the vehicle. The mechanical key, in normal operation,
will turn the Passlock™ lock cylinder. The Passlock™ sensor, which is
mounted to the Passlock™ lock cylinder assembly, sends data by circuit 1836
to the BCM. The Passlock™ sensor is powered by circuit 812 from the
BCM. The Passlock™ sensor is grounded by circuit 1057 to the BCM. The
BCM determines the validity of the Passlock™ sensor data within a preset time
window based on the ignition switch input. The BCM will then send a coded password
to the ECM by the CAN bus circuit 3204 or PCM by class 2, circuit 1807.
When the ECM/PCM receives the correct code, it will allow the fuel injectors to operate
normally.
Passlock™ Modes
| | The pass theft mode is normal operation. During a normal start up, the SECURITY
telltale will turn on. The telltale will turn off when: |
| - | The ignition is turned to the OFF or ACC position |
| - | The ignition is turned to the START position and a 3 second timer
has expired. |
| • | Short Tamper Mode (Fuel Disable Timer Mode) |
| | The PCM or ECM enters the short tamper mode if the ECM detects an open voltage
code, 4.43-5.00 V. The BCM will send out the fuel undecided password
to the PCM. The PCM will disable the fuel supply to the engine for 4 seconds. |
| | The driver usually observes a start quickly followed by a stall when in the
short tamper mode. After 4 seconds a start may again be attempted, except in
one situation. |
| | If the PCM/ECM receives the wrong password, for example a new BCM was installed
without following the relearn procedure, the security telltale will flash for 4 seconds
and remain on, and the fuel injectors will remain disabled until the correct relearn
procedure has been completed. |
| | The BCM enters the long tamper mode if the BCM receives the wrong voltage code
at an attempted start. The BCM will then send a disable fuel message to the PCM/ECM.
The PCM/ECM will then disable the fuel injectors. |
| | The driver experiences the same start quickly followed by a stall. The fuel
will be disabled for 10 minutes and the security telltale will also flash. |
| | In the fail enable mode, the engine is allowed to run normally because the fault
occurred while the engine was running. The security telltale will remain on whenever
the engine is running to alert the driver there is a problem with the Passlock™
system and there is no Passlock™ system protection. The engine can be restarted
in the fail enable mode. |
| | Whenever the engine is running, the Passlock™ system constantly monitors
itself. The BCM monitors the circuits between itself and the Passlock™ sensor.
The BCM and PCM/ECM also monitor each other through the serial data link. If a problem
is detected, diagnostic trouble codes will set and the security telltale will be on
when the engine is running. |
Diagnostic Trouble Codes
In either the short or long tamper mode, the BCM or the PCM/ECM will set diagnostic
trouble codes. Each module should be checked for DTCs.
