General Information

B1203 Heater Water Temperature Sensor Short (Low)

General Information

Component Location





General Description

Engine coolant temperature sensor is located in the engine coolant passage of the cylinder head for detecting the engine coolant temperature. It contains negative type thermistor whose resistance value is in inverse proportion to temperature. Resistance of water sensor that varies with temperature makes signal voltage of A/C ECU change. In this way A/C ECU detects temperature. Signal of water sensor is used for cold engine lockout control - When the driver operates the heater before the engine is warmed up enough, to prevent driver from unpleasantness of cold air. the heater control unit reduces blower motor speed until coolant temperature reaches the threshold value.

DTC Description

Air conditioner Control Module sets DTC B1203 if Engine coolant temperature sensor signal has been detected open or below 0.1 V for 0.3 sec.

DTC Detecting Condition





Specification

** Resistance value of Engine coolant temperature sensor as a function of temperature.






Diagnostic Circuit Diagram