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.