Coolant Temperature Sensor/Switch (For Computer): Description and Operation

Coolant Temperature Sensor:

PURPOSE
The Engine Coolant temperature sensor provides the ECM with information regarding the engine coolant temperature for proper adjustment of injection duration and ignition timing.

LOCATION
Center port of thermostat housing.

CONSTRUCTION
The Engine Coolant temperature sensor is an NTC resistor. As engine temperature rises, resistance decreases.

SIGNAL APPLICATION
Coolant temperature sensor signals are required as a correction factor for ignition timing, injection time, and idle speed stabilization.

If the Engine Coolant temperature sensor fails, a substitute value of 176° F (80° C) is stored in ECM memory.

In addition, the following systems are engine temperature dependent:
- Knock Control
- Idle Speed Volume Control Adaptation
- Oxygen Sensor Operation
- Fuel Tank Venting

SELF DIAGNOSIS
ECM diagnostics recognize short circuit to ground or positive.