Passlock General Description

The passlock system is a vehicle theft deterrent system which deters drive-away vehicle theft by disabling 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 security hall effect sensor, 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 two 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 body control module (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 engine control module (ECM) is used on the L81 engine applications. The coded password for the security system is sent from the body control module 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 powertrain control module (PCM) is used on L61 engine applications. The coded password for the security system is sent from the body control module 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 instrument panel cluster (IPC) contains the security telltale. The security telltale has three modes of operation, OFF, FLASHING, and ON.

SECURITY TELLTALE will be OFF if:
^ Ignition is in the OFF position
^ Ignition is in the RUN, START, or ACC position and security system diagnostics have all PASSED

SECURITY TELLTALE will be ON if:
^ The BCM is performing a bulb check at vehicle start
^ 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
^ Incorrect passlock sensor data to BCM for more than 5 seconds during vehicle start
^ No passlock sensor data to the BCM for more than 5 seconds during vehicle start
^ Incorrect password from the BCM to the ECM/PCM after 5 seconds during vehicle start
^ The security telltale will also flash when content theft system is in the armed mode.