Intrigue V6-3.8L VIN K (1998)
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Day/night mode sensing: The BCM determines the ambient light operating mode from the Daytime Running Lamp (DRL) control module. Then, it
communicates this information to the instrument cluster and Powertrain Control Module (PCM) via the Class 2 serial data link.
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 an analog voltage signal
of a different value. The BCM compares the preset stored analog voltage value with the signal coming from the sensor. Because both values do not
match, the BCM sends a fuel disable password via the Class II serial data link to the PCM. As a result, the PCM disables the crank relay, and does not
allow fuel delivery to the engine.
System Description
This vehicle is equipped with a Body Control Module (BCM). The BCM performs multiple body and engine control functions. Several vehicle systems
are directly connected to the BCM, such as the audible warnings, interior lighting, door locks, keyless entry, and the Passlock theft deterrent.
This vehicle also has other systems, such as the Powertrain Control Module (PCM), the Electronic Brake Traction Control Module (EBTCM), and the
Instrument Panel Cluster (IPC). These vehicle systems communicate with each other on an interconnecting bus, known as the Class II serial data link.
Some electrical components are directly connected and controlled by their system module. Other systems accomplish this by sharing data information
with other systems on the Class II serial data link to execute various vehicle functions. All system data information (sensors, switches, etc.) can be
monitored by any system module that completes the computer system.
All systems on the Class II serial data link use a communication process similar to a telephone system, where enormous amounts of information can be
exchanged on a single data wire.
Communications between each system is accomplished by sending a digitally coded message, consisting of specific information a system module must
follow. Each system module is assigned its own recognition code (address). Thus, when a message is sent out on the Class II serial data link, only the
particular system module that was assigned that recognition code will respond to the message.
By communicating data information with other systems on the Class II serial data link, the BCM provides more accurate and reliable computer system
control functions. The BCM uses information from other systems in order to execute some functions. Therefore, before further diagnosis, review the
general information on how the BCM computer system operates and how each system interacts with the BCM. This will save diagnostic time, avoid
misdiagnosis, and prevent unnecessary parts replacement.
