Passlock Theft Deterrent
The Passlock is a vehicle theft deterrent system. The Passlock theft
deterrent system contains a Passlock sensor. The Passlock sensor is part of
the ignition lock cylinder assembly. The Body Control Module (BCM) provides
power and ground to the Passlock sensor. The Passlock sensor interfaces
with the BCM through the Passlock detection circuit 1836.
When turning the ignition switch to the start position with the proper
key, the Passlock sensor generates an analog voltage signal. This signal is
sent through the Passlock detecting circuit. This analog voltage signal
is of a specific value to the vehicle, and varies from vehicle to vehicle.
When attempting to start the engine, the BCM compares a preset stored analog
voltage value with the signal coming from the sensor. Because both values
match, the BCM sends a fuel enable password via the Class II serial data
link to the Powertrain Control Module (PCM). As a result, the PCM enables
the crank relay, and allows fuel delivery to the engine.
When attempting to start the engine by means other than using the proper
key in the ignition switch, the Passlock sensor sends a analog voltage signal
of a different value. The BCM compares the preset stored analog voltage
value with the signal coming from the Passlock sensor. Because both values
do not match, the BCM sends a fuel disable password via the Class II serial
data link to the Powertrain Control Module (PCM). As a result, the PCM disables
the crank relay, and does not allow fuel delivery to the engine.
Refer to
Body Control System Description
for more information regarding the BCM.
Diagnostic Trouble Codes (DTCs)
The BCM may set these DTCs related to the Passlock theft deterrent system:
Refer to
Body Control Module Diagnostic Information
in Body Control System for more information.
BCM Inputs
The following components provide direct input to the BCM, plus other
systems can use this input information in order to carry out Passlock theft
deterrent functions:
| • | BCM Ground: Provides ground for BCM operation. |
| • | BCM Power: Provides voltage for BCM operation. |
| • | Crank Signal: Determines when the ignition switch is in the start
position. |
| • | Ignition 0 Signal: Determines when the ignition switch is in accessory,
on, and start positions. |
| • | Ignition 1 Signal: Determines when the ignition switch is in the
on, bulb test, and start positions. |
| • | Passlock Sensor Data: Reads the Passlock sensor security code. |
| • | Serial Data: provides an interface with the PCM through the Class
II serial data link. |
BCM Outputs
The BCM directly controls these outputs for Passlock theft deterrent
functions:
| • | Passlock Sensor Power: Provides B+ for Passlock sensor operation. |
| • | Passlock Sensor Ground: Provides ground to the Passlock sensor. |
| • | Serial Data: provides an interface with the PCM and the instrument
cluster through the Class II serial data link. |
Theft Deterrent Re-Learn
Perform the Theft Deterrent Re-Learn procedure when:
| • | The BCM has been replaced in the vehicle and the Setup New BCM
procedure has been successfully completed. |
| • | The ignition key cylinder assembly has been replaced. |
Refer to
Body Control Module (BCM) Programming/RPO Configuration
in Body Control System
for the Theft Deterrent Re-Learn and the Setup New BCM service procedures.
