Water temp sensor located at heater unit detects coolant temperature. Its signal is used for cold engine lookout control. When the driver operates heater to warm before the engine is warmed up, the signal from sensor is delivered to the heater control unit and according to this signal, heater control unit reduces blow motor speed untill coolant temperature is up to threshold value
The ECM sets DTC B1203 if there is a short circuit in water temp sensor signal harness or the measured resistance value of sensor is less than threshold value(about 1.2㏀)
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Voltage check | ● Short circuit in harness ● Fault water temp. Sensor ● Fault A/C Control Unit |
Threshold value | ● < 0.1V | |
Detecting time | ● 0.3sec | |
FAIL SAFE | ● Control with the vlaue of 20℃ |
Temperature(℃) | Resistance(㏀) | Temperature(℃) | Resistance(㏀) |
-30 | 176.3 | 25 | 10 |
-15 | 73.6 | 35 | 6.5 |
0 | 32.9 | 60 | 2.5 |
15 | 15.8 | 80 | 1.2 |
