GM Service Manual Online
For 1990-2009 cars only

CHECK OIL LEVEL Indicator (Buick)

The oil level sensing system consists of the following components:

    • An oil level sensor
    • The powertrain control module (PCM)

The oil level is indicated in the following manner:

  1. The oil level sensor provides the oil level signal to the PCM on CKT 1174 (BRN).
  2. The PCM processes the signal.
  3. If the PCM determines that a low oil level condition exists, the PCM grounds CKT 1173 (BRN/WHT).
  4. The CHECK OIL LEVEL indicator illuminates.

CRUISE Indicator

The cruise indicator illuminates in the following manner:

  1. The instrument cluster receives cruise data from the powertrain control module (PCM) over the universal asynchronous receiving/transmitting (UART) serial data line.
  2. The instrument cluster converts the serial data.
  3. The PCM commands the instrument cluster to illuminate the CRUISE indicator.

LOW COOLANT Indicator (Buick)

The low coolant indicator illuminates in the following manner:

  1. The engine coolant level sensor provides a signal to the instrument cluster on CKT 68 (YEL/BLK).
  2. If the engine coolant level is low, the sensor grounds CKT 68.
  3. The LOW COOLANT indicator illuminates.

LOW WASHER FLUID Indicator (Buick)

The low washer fluid level indicator illuminates in the following manner:

  1. The windshield washer solvent level switch provides a signal to the instrument cluster on CKT 99 (BLK/WHT).
  2. If the washer fluid is low, the sensor grounds CKT 99.
  3. The LOW WASHER FLUID indicator illuminates.

OIL Indicator

The oil indicator illuminates in the following manner:

  1. The engine oil pressure switch provides a signal to the instrument cluster on CKT 231 (TAN/BLK).
  2. If the oil pressure is low (below 2 psi) the switch is closed, grounding CKT 231.
  3. The OIL indicator illuminates.

VOLTS Indicator

The volts indicator illuminates in the following manner:

  1. The instrument cluster receives charging data from the powertrain control module (PCM) over the universal asynchronous receiving/transmitting (UART) serial data line.
  2. The instrument cluster converts the serial data.
  3. The PCM commands the instrument cluster to illuminate the VOLTS indicator.