K Tahoe 4WD V8-4.8L VIN V (2000)
Body Control Module: Description and Operation
Body Control System Description
BCM FUNCTIONS
The body control module (BCM) is capable of controlling multiple body functions. Components directly connected to the BCM are controlled by the
BCM's outputs. The BCM controls the outputs based on input information that it obtains from the sensors and the switches that are directly connected
to it. The BCM can also borrow information from other vehicle systems connected to the Class 2 serial data link. The BCM evaluates this information
and controls certain body systems by commanding an output ON or OFF.
The BCM is also capable of commanding other vehicle systems to control functions that are not directly wired and/or controlled by the BCM. The
BCM accomplishes this task by sending specific messages on the Class 2 serial data link. The vehicle system capable of performing such function will
respond to the BCM message.
The BCM controls the following functions:
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Audible Warnings
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Indicator Warnings
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Interior Lighting
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Exterior Lighting.
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Power Door LOCK/UNLOCK
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Remote Keyless Entry
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Passlock Theft Deterrent
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Content Theft Deterrent
AUDIBLE WARNINGS
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Key in ignition reminder
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Fasten seat belt reminder
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Park brake reminder
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Turn signal reminder
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Headlamps ON reminder
INDICATOR WARNINGS
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Security indicator
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Cargo lamp on indicator
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Fasten belts indicator
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Park brake indicator
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Tow/Haul indicator
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High beam indicator
INTERIOR LIGHTING
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Interior illumination control
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Delayed illumination
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Illuminated entry
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Exit illumination
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Keyless entry unlock illumination
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Inadvertent power (battery rundown) protection
POWER DOOR LOCKS
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All door unlock
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All door lock
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Lockout prevention
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Automatic (rolling) door lock
KEYLESS ENTRY
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Remote driver door unlock
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Remote all door unlock
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Remote all door lock
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Remote panic alarm
PASSLOCK THEFT DETERRENT
Passlock is a vehicle theft deterrent system. This system contains an ignition key sensor called a Passlock sensor. The Passlock sensor is part of the
ignition lock cylinder assembly. The BCM provides power and ground for the Passlock sensor.
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 2 serial data link to the powertrain control module (PCM) or the vehicle control module (
