Temperature Switch


  • Drain the coolant from the radiator and remove the temperature switch.
  • Place the temperature switch and a thermometer in a heat-resistant container with water. The switch should be submerged.
  • Be sure the water temperature is below 99° F (37° C).
  • Connect an ohmmeter to the temperature switch terminals and heat the water while observing the thermometer.
  • When the temperature is below 99° F, the temperature switch contacts should be closed and the ohmmeter should be zero ohms.
Mechanically controlled mixture heater system. Courtesy of Nissan Motors.
  • Above this temperature, the ohmmeter reading should be infinity.
  • If the switch fails this test, it should be replaced.