Coolant Level Switch

The coolant level switch senses presence or absence of coolant in pressurized coolant overflow bottle using a float. When float is suspended in coolant, switch will be open. When float is not suspended in coolant, switch will close, indicating low coolant level. The PCM monitors state of coolant level switch through CKT 1478. When coolant level switch is open, CKT 1478 is at 12 volts, indicating adequate coolant level. When switch closes to indicate low coolant, CKT 1478 is grounded through CKT 450.