Coolant Level Sensor: Description and Operation

Coolant Level Switch Location:

PURPOSE
The Powertrain Control Module (PCM) checks the engine coolant level continuously. If the coolant level switch indicates low coolant level at any time, the PCM will send information through serial data to the instrument cluster to turn "ON" the "Low Coolant Level" telltale.

OPERATION
The coolant level switch is an assembly containing a reed switch and magnetic float. When the coolant level is normal, the float rests away from the reed switch, causing the switch to open. When the coolant level is low, the float rests near the reed switch and the switch closes.

The coolant level switch is mounted in the radiator surge tank to monitor radiator coolant level. The coolant level switch is a normally open switch. If coolant falls below a specified level, the switch closes sending a ground signal to the PCM. The PCM in turn will send information through serial data to the instrument cluster. The cluster will then turn "ON" the low coolant level telltale.