Alero L4-144 2.4L DOHC VIN T SFI (2000)
Check Oil Indicator (V6 Only)
The amber check oil indicator illuminates when the PCM reads the oil level switch and transmits a Class 2 message to instrument cluster indicating a low
oil level condition. If the low oil level option is false, all Class 2 activity on the instrument cluster stops. The instrument cluster will not send out any
request for the low oil level condition command and will not issue a low oil level condition report. If a loss of PCM Class 2 serial data occurs, the check
oil indicator will not illuminate unless the indicator was illuminated when the event occurred.
High Temperature Indicator
The high temperature indicator function handles the control of the engine temperature gauge display and the red high temperature indicator. The PCM
reads the coolant temperature sensor, filters the messages, and sends the coolant temperature to the instrument cluster via a Class 2 serial data message.
The PCM monitors the coolant sensor in order to determine a fault. The PCM transmits the Class 2 serial data coolant temperature report messages to the
instrument cluster for the temperature gauge display and for the high temperature indicator control.
The instrument cluster receives the engine temperature data in the Class 2 serial data message from the PCM. The instrument cluster converts this data
into a temperature gauge pointer position which drives the gauge pointer. The instrument cluster also uses this data in order to determine the high
temperature indicator control.
The BCM looks for the high temperature indicator Class 2 serial data report from the instrument cluster and triggers a chime when the indicator is on.
High Beam Indicator
The blue high beam indicator is a distributed function between the BCM and the instrument cluster. The BCM reads the high beam bulb voltage, and
divides by the system voltage in order to determine a percent value. This value is compared against a calibration in order to determine if the high beams
are on. The BCM then transmits the status of the high beams to the instrument cluster via the Class 2 serial data bus. The instrument cluster then
commands the high beam indicator accordingly. In the event of a Class 2 data link failure, the high beam indicator will not illuminate unless the indicator
was illuminated prior to the Class 2 data link failure.
Low Engine Coolant Indicator
The red low coolant indicator illuminates in order to indicate to the driver that the engine coolant level is low. The engine coolant level switch is a
discrete input to the BCM which closes when the engine coolant is low. The indicator illuminates when the input has been active low for at least 10
seconds and the ignition switch is in the ON position. The indicator is commanded off if the switch input goes inactive for at least 2 seconds. This is a
distributed function between the BCM and the instrument cluster. The BCM reads the status of the engine coolant level switch input in order to
determine the indicator control. Then the BCM sends the control state to the instrument cluster via the Class 2 serial data bus. The instrument cluster
reads the low coolant indicator control state in the Class 2 serial data message and controls the indicator directly. It a Class 2 data link fails, the low
coolant indicator illuminates.
Low Fuel Indicator
The amber low fuel indicator turns on in order to indicate to the driver that the fuel level has dropped to a calibrated point below 1/16 of a tank. The
indicator is turned off when the fuel level rises back above 1/16 of a tank. The fuel level is determined from the fuel level sense and display function and
is then used by the low fuel indicator. This is a distributed function between the PCM and the instrument cluster. The instrument cluster reads the low
fuel indicator control state in the Class 2 message and controls the indicator directly. If a Class 2 data link fails, the low fuel indicator does not illuminate
unless the indicator was illuminated prior to the Class 2 data link failure.
Low Wash Indicator
The amber LOW WASH indicator turns on in order to indicate to the driver that the washer fluid level is low. The low washer fluid level switch is a
discrete input to the BCM which closes when the washer fluid level is low. The BCM commands the instrument cluster to illuminate the indicator when
the input has been active for a calibratable time (at least 30 seconds). The BCM commands the instrument cluster to turn the indicator off, if the switch
input goes inactive for a calibratable time (at least 30 seconds). If a Class 2 data link fails, the LOW WASH indicator does not illuminate unless the
indicator was illuminated prior to the Class 2 data link failure.
Oil Pressure Indicator
The red oil pressure indicator turns on when the PCM transmits a Class 2 message to the instrument cluster indicating a low oil pressure condition. The
instrument cluster commands the oil pressure indicator on over the Class 2 serial data interface. If a loss of Class 2 serial data occurs, the oil pressure
indicator does not illuminate unless the indicator was illuminated when the event occurred. If a Class 2 data link fails, the oil pressure indicator does not
illuminate unless the indicator was illuminated prior to the Class 2 data link failure.
PRNDL
The PCM reads the transaxle range switch and transmits the selected gear position over the Class 2 serial data link to the instrument cluster.
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On the Oldsmobile, the instrument cluster must turn on the correct gear indicator and perform the scrolling function.
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The Pontiac gear indicator is in the console.
Seat Belt Indicator
The seat belt switch is a discrete input to the BCM which opens when you insert the seat belt into the buckle. The BCM commands the instrument cluster
to illuminate the red seat belt indicator under either of the following conditions:
