Alero L4-144 2.4L DOHC VIN T SFI (2000)
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The seat belt switch is active when Ignition 1 changes from inactive to active
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While Ignition 1 is active and the seat belt input changes from inactive to active.
Upon either transition, the seat belt indicator glows steady for 20 seconds and then flashes at 1 Hz for 55 seconds. The indicator turns off when any one
of the following conditions becomes true:
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At the end of the 75 seconds
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If the seat belt input becomes inactive
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If Ignition 1 becomes inactive
If a Class 2 data link fails, the seat belt indicator does not illuminate unless the indicator was illuminated prior to the Class 2 data link failure.
SERVICE VEHICLE SOON Indicator
The amber SERVICE VEHICLE SOON indicator is an alert to the driver whenever there are specific current codes stored in the BCM or in the event of
a loss of Class 2 serial data.
Security Indicator
The red SECURITY lamp illuminates when the Passlock(R) data is incorrect. The BCM sends to the instrument cluster via the Class 2 serial data bus the
message to turn on or off the SECURITY indicator. The SECURITY indicator turns on under either of the following conditions:
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Any theft deterrent DTC is set.
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The PCM VTD Fail/Enable bit is true in the last vehicle security status message received and the BCM is not in the auto-learn mode.
The SECURITY indicator flashes when the BCM detects a tamper or the PCM fuel disable time-out bit is set in the last vehicle security status message
received since the ignition switch was turned to the ON position.
Exterior Lighting Control
The BCM controls exterior lighting Systems which includes the following:
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ALC headlamps and parklamps
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Daytime Running Lights (DRL)
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Front foglamps
Daytime Running Lights (DRL) operate the headlamps (Pontiac) or high beams only (Oldsmobile) at a reduced intensity under the following conditions:
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When the vehicle is not in park
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When the park brake is not set
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When the normal headlamps are not on
The DRL activates if the transmission is not in PARK and the park brake is off. The DRLs remain on and latch on if the park brake is on and the vehicle
speed is above the threshold. The vehicle is defined to be in motion if the transmission is not in PARK and the park brake is not set.
Automatic lighting control turns on the parklamps and the headlamps when the ambient light sensor detects a low ambient light level. The system assures
that the headlamps/parklamps are on if the driver is operating the vehicle after dark.
If the ignition switch is turned to the ON position in a low ambient light level area, the automatic lighting control becomes active immediately, otherwise
8 seconds must elapse before the automatic lighting control is activated. If the park brake is set when the ignition switch is turned to the ON position, the
automatic lighting control is disabled until the park brake is released. If the automatic lighting control is active and a high ambient light level is detected,
20 seconds must elapse before the automatic lighting control is turned off. The headlamps are disabled during engine crank.
The front foglamp relay activates when all of the following conditions occur:
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The ignition switch is on.
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The parklamps are on.
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The highbeam headlamps are off.
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The foglamp switch is pressed.
Foglamp relays are always off whenever a short to battery fault is detected on the foglamp relay output driver.
The backup lamps are the only exterior lamps that are not controlled by the BCM.
Engine Coolant Temperature
The BCM handles the control of engine temperature gauge display and the high temperature indicator. The PCM reads the engine coolant temperature
sensor, filters the data, and sends the engine coolant temperature to the instrument cluster via a Class 2 serial data message. The PCM transmits the Class
2 serial data coolant temperature report messages to the instrument cluster in order to determine the temperature gauge display and to the high
temperature indicator control.
The instrument cluster receives the engine temperature data in the Class 2 serial data message from the PCM and converts this message into a
temperature gauge pointer position which drives the gauge pointer. The instrument cluster also uses this message in order to determine the high
