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 themistor whoses resistance value is in inverse proportion to temperature. Resistance of watersensor 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.
Air conditioner Control Module sets DTC B1203 if Engine coolant temperature sensor has been detected open or below 0.1V for 0.3sec.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Voltage check |
•
Poor connection in wireharness
•
Open in signal circuit
•
Short to battery in signal circuit
•
Faulty Engine coolant temperature sensor
•
Faulty A/C Control Unit |
Enable Conditions |
•
IG KEY ON | |
Threshold value |
•
Engine coolant temperature sensor has been detected open or below 0.1V for 0.3sec. | |
Failsafe |
•
Control with the value of -2℃(28.4℉) |
Temperature(℃/℉) | Resistance(㏀) | Temperature(℃/℉) | Resistance(㏀) |
-20(-4) | 14.13 ~ 16.83 | 40/104 | 1.15 |
0/32 | 5.79 | 60/140 | 0.59 |
20/68 | 2.31 ~ 2.59 | 80/176 | 0.32 |
