Malibu V6-191 3.1L VIN M SFI (1997)
Body Control Module: Description and Operation
Body Control System Operation
Bulb Check General Description
The bulb check function resides in the Body Function Controller (BFC). Every time the Ignition Switch transitions from ACC to RUN, an Instrument
Cluster bulb check will occur for a calibrated amount of time for specified indicators. Bulb check will override the OFF state of the affected indicators.
The Body Function Controller (BFC) will determine which indicators to bulb check by looking at an EEPROM table. Every Serial Peripheral Interface
(SPI) indicator has a bit in the EEPROM table. The gauges will WOW during a bulb check. A WOW is when all of the gauge indicators are moved at the
same time and all indicators are lit. If there is an indicator lit before the WOW, the indicator shall remain lit after this function has concluded.
Compressor Controls
The Powertrain Control Module (PCM) and Body Function Controller (BFC) share hardware and software for control of the AC Compressor Clutch.
The Powertrain Control Module (PCM) and the Body Function Controller (BFC) communicate this information over the serial data Class 2 line.
The Body Function Controller (BFC) performs the following software functions:
^
Limit Low Speed Compressor Operation
^
Prevent Clutch Slippage
^
High Coolant Temperature
^
Monitor for Overpressure
^
Determine Low Ambient Pressure
^
Control Compressor Clutch
The Powertrain Control Module (PCM) performs the following functions:
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Prevent Compressor Overspeed
^
Limit Compressor Speed (in PARK or NEUTRAL)
^
Drive Compressor Clutch
^
Perform Anti-Slug (Slugging is when a mass of liquid enters the AC Compressor Pump)
Interior Lighting Control
The Body Function Controller (BFC) provides the following interior lamp control:
^
Courtesy lamps.
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Illuminated Entry control of Courtesy Lamps.
Courtesy Lamps are enabled by the following methods:
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By discrete input to the Body Function Controller (BFC) from the door ajar switches.
^
If any of the doors are open and the vehicle speed is less than 13 km/h (8 mp/h).
^
If the Ignition Switch has been turned OFF for less than two minutes and then the doors are closed, the lights will stay on for 4 seconds (or
until the Ignition Switch is turned to the RUN position).
^
If the Ignition Switch has been turned OFF for more than two minutes and then the doors are closed, the lights will stay on for 40 seconds (or
until the Ignition Switch is turned to the RUN position).
^
If the Ignition Switch has been turned OFF for less than two minutes and the Ignition Key is removed or the doors are opened, the lights will
turn on for 15 seconds (or until the Ignition Key is re-inserted or a door open switch is cycled).
^
Remote Control Door Lock Transmitter activation of the Driver Door Unlock or the Trunk Release (function of Illuminated entry).
When the interior lights are to be turned off because a customer is leaving the vehicle (the Ignition Switch is turned OFF for more than two minutes),
they are first step dimmed, and then theater dimmed to the OFF state. If the Ignition Switch is turned OFF for less than two minutes the interior lights are
theater dimmed to the OFF state in four seconds. If the customer sits in the vehicle and the interior lights have turned OFF and the customer removes the
Ignition Key the interior lights will illuminate for 15 seconds.
Volts Indicator
The Volts indicator (red) will be illuminated under the following conditions:
^
Lamp Terminal pulled low:
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Key On (Bulb check)
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Open Field or Regulator Circuit
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Output voltage above overvoltage set point (no control)
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Low system voltage above Engine RPM calibrated value (Undervoltage)
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Open P terminal at the Voltage Regulator, shorted positive or negative bridge diode at P terminal Field terminal voltage
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Condition indicate a voltage regulator disconnect (Low Duty Cycle)
The Powertrain Control Module (PCM) will determine Engine RPM, Generator Field Duty Cycle, Lamp Terminal State, L term disabled and send these
as Class 2 messages to the Body Function Controller (BFC). The Body Function Controller (BFC) will then dictate to the Instrument Cluster the state of
the Volts indicator and set the appropriate fault codes.
