Cavalier L4-2.2L VIN F (2004)
Body Control Module: Description and Operation
Body Control Module (BCM)
BODY CONTROL MODULE
The various BCM input and output circuits are described in the corresponding functional areas indicated on the BCM electrical schematics. The Body
Control Module functions include the following.
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Retained Accessory Power, RAP, Audio System only.
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A/C compressor request.
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Remote Function Control.
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A/C cooling Fan.
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Exterior and interior lighting control
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Daytime running lights (DRL)
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Automatic lighting control
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Fog lamps
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Interior lighting.
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Battery rundown protection (Inadvertent Power).
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Chimes.
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Key In Ignition
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Head Lamps On
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Seat Belt Not Fastened
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Turn Signal On
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Park Brake Warning
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Door Ajar Warning
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Check gauges
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Gauge control.
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Instrument cluster indicator control.
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Theft deterrent.
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Engine coolant level sensing.
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Key-in-ignition sensing.
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Brake fluid level sensing.
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Parking brake state sensing.
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Rear compartment interface.
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Horn interface.
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Door lock interface.
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Bulb Check.
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ETS -Pontiac Only.
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A/T Shift lock control.
The BCM contains the logic of the theft deterrent system. The BCM provides the battery positive voltage to operate the Passlock(TM) Sensor. The BCM
also measures the voltage of the security sensor signal circuit. The voltage measured will indicate whether the Passlock(TM) Sensor has been activated
and whether the resistance value from the sensor is a valid value or the tamper value. If voltage measured is in the valid range, the BCM compares this
voltage, voltage code, to a previously learned voltage code. If the voltage codes match, the BCM sends a class 2 message containing a password to the
PCM. If the voltage codes do not match, or the voltage is in the Tamper range, or there is a circuit fault, the BCM will not send the correct password to
the PCM, and the vehicle will not start.
