It contains a thermistor which measures the temperature of the inside. The signal,decided by the resistance value which changes in accordance with perceived inside temperature, is delivered to heater control unit. According to this signal, the control unit regulates incar temperature to intended value.
DTC B1234 sets if In-Car temperature sensor signal is at or over 4.9V for 0.3 seconds.
Item
Detecting Condition
Possible Cause
DTC Strategy
Voltage check
Poor connection in wireharness
Open in signal circuit
Short to battery in signal circuit
Faulty Incar temperature sensor
Faulty Air conditioner Control Module
Enable Conditions
IG KEY ON
Threshold value
Sensor signal is at or over 4.9V for 0.3 seconds
Fail safe
Substituded In-Car Temp. = 25? (77?)
? Resistance value of incar temp sensor as a function of temperature.
Temperature(?/?)
Resistance(?)
-30/-22
509
25/77
30
-15/5
216
35/95
19
0/32
97.7
50/122
10.8
15/59
47
60/140
2.6