AIR CONDITIONING SYSTEM(for Automatic Air Conditioning System), Diagnostic DTC:B1412/12
| DTC Code | DTC Name |
|---|---|
| B1412/12 | Ambient Temperature Sensor Circuit |
DESCRIPTION
The cooler thermistor (ambient temperature sensor) is installed in the front part of the condenser assembly with receiver to detect the ambient temperature and control the air conditioning auto mode. The sensor connected to the air conditioning amplifier assembly detects fluctuations in the ambient temperature. This data is used for controlling the room temperature. The sensor sends a signal to the air conditioning amplifier assembly. The resistance of the ambient temperature sensor changes in accordance with the ambient temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.
The combination meter assembly applies a voltage (5 V) to the cooler thermistor (ambient temperature sensor) and reads voltage changes as changes in the resistance of the cooler thermistor (ambient temperature sensor). The combination meter assembly sends the signal to the air conditioning amplifier assembly via CAN communication.
DTC Code |
DTC Detection Condition |
Trouble Area |
|---|---|---|
B1412/12 |
An open or short in the ambient temperature sensor circuit. |
|
WIRING DIAGRAM
PROCEDURE
CHECK CAN COMMUNICATION SYSTEM
Use the intelligent tester to check if the CAN communication system is functioning normally.
OK
CAN DTC is not output.
READ VALUE USING INTELLIGENT TESTER
Use the Data List to check if the cooler thermistor (ambient temperature sensor) is functioning properly.
Table 1. Air Conditioner Tester Display
Measurement Item/Range
Normal Condition
Diagnostic Note
Ambient Temp Sensor
Ambient temperature sensor /
Min: -23.3°C (-9.94°F)
Max: 65.95°C (150.71°F)
Actual ambient temperature displayed
Open in the circuit: -23.3°C (-9.94°F).
Short in the circuit: 65.95°C (150.71°F).
OK
The display is as specified in the normal condition column.
Table 2. Result Result
Proceed to
OK (When troubleshooting according to Problem Symptoms Table)
A
OK (When troubleshooting according to the DTC)
B
NG
C
INSPECT COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR)
for 1WW:
Remove the ambient temperature sensor (Click here).
except 1WW:
Remove the ambient temperature sensor (Click here).
Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection
Condition
Specified Condition
1 - 2
10°C (50°F)
3.00 to 3.73 kΩ
15°C (59°F)
2.45 to 2.88 kΩ
20°C (68°F)
1.95 to 2.30 kΩ
25°C (77°F)
1.60 to 1.80 kΩ
30°C (86°F)
1.28 to 1.47 kΩ
35°C (95°F)
1.00 to 1.22 kΩ
40°C (104°F)
0.80 to 1.00 kΩ
45°C (113°F)
0.65 to 0.85 kΩ
50°C (122°F)
0.50 to 0.70 kΩ
55°C (131°F)
0.44 to 0.60 kΩ
60°C (140°F)
0.36 to 0.50 kΩ
Note:Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
When measuring, the sensor temperature must be the same as the ambient temperature.
Tip:As the temperature increases, the resistance decreases (refer to the graph).
Table 3. Result Result
Proceed to
OK
A
NG (for 1WW)
B
NG (except 1WW)
C
CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR - COMBINATION METER)
Disconnect the A25 sensor connector.
Disconnect the H62 meter connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection
Condition
Specified Condition
A25-1 - H62-33 (TEMP)
Always
Below 1 Ω
A25-2 - H62-25 (TX1+)
H62-33 (TEMP) - Body ground
Always
10 kΩ or higher
H62-25 (TX1+) - Body ground
Table 4. Text in Illustration *1
Front view of wire harness connector
(to Ambient Temperature Sensor)
*2
Rear view of wire harness connector
(to Combination Meter Assembly)
REPAIR OR REPLACE HARNESS OR CONNECTOR