Temperature Indicator
System consists of a "TEMP" or "ENGINE" light and a normally open-to-ground temperature sensing switch. When coolant temperature reaches approximately 249° F, switch closes circuit to ground, turning on the indicator light. As a test of proper bulb operation, the light will also turn on with the ignition in the "START" position.
NOTE:
On models with Automatic Temperature Control type air conditioning systems, the temperature sending unit has two terminals. The terminal marked "R" (gauge equipped) or "C" (indicator light equipped) provides a ground circuit for cold engine override (below 115°F engine temperature) of heater blower motor.