Description
DATA TROUBLE CODE: 22SYSTEM: Engine Coolant Temperature Sensor Circuit
CIRCUIT DESCRIPTION
The engine coolant temperature sensor senses the engine coolant temperature. A thermistor built in the sensor changes the resistance value according to the engine coolant temperature. The lower the engine coolant temperature, the greater the thermistor resistance value, and the higher the engine coolant temperature, the lower the thermistor resistance value.
The engine coolant temperature sensor is connected to the engine control module. The 5.0 volt power source voltage in the engine control module is applied to the engine coolant temperature sensor from the terminal THW via a resistor R. That is, the resistor R and the engine coolant temperature sensor are connected in series. When the resistance value of the engine coolant temperature sensor changes in accordance with changes in the engine coolant temperature, the potential at the terminal THW also changes. Based on this signal, the engine control module increases the fuel injection volume to improve driveability during cold engine operation. If the engine control module detects the diagnostic trouble code 22, it operates the fail safe function in which the engine coolant temperature is assumed to be 80°C (176°F).
DIAGNOSTIC TROUBLE CODE DETECTING CONDITION
- pen or short in engine coolant temperature sensor circuit for 0.5 seconds or more.
TROUBLE AREA
- Open or short in engine coolant temperature sensor circuit.
- Engine coolant temperature sensor.
- Engine control module.
Malfunction Indicator Lamp
Normal Mode On
Test Mode On