HEATING / AIR CONDITIONING AIR CONDITIONING SYSTEM(for Manual Air Conditioning System) B1412 Ambient Temperature Sensor Circuit
DESCRIPTION
The thermistor assembly is installed in front of the cooler condenser assembly to detect the ambient temperature, which is used to control the air conditioning system. This sensor is connected to the combination meter assembly and detects fluctuations in the ambient temperature. This data is used for controlling the cabin temperature. The sensor sends a signal to the combination meter assembly. The resistance of the thermistor assembly 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 voltage (5 V) to the thermistor assembly and reads voltage changes due to changes in the resistance of the thermistor assembly.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | Memory |
|---|---|---|---|---|
| B1412 | Ambient Temperature Sensor Circuit | Open or short in ambient temperature sensor circuit | ·
Thermistor assembly ·
Harness or connector between thermistor assembly and combination meter assembly ·
Air conditioning amplifier assembly ·
Combination meter assembly ·
CAN communication system |
Memorized
(4 sec. or more)* |
*: The air conditioning amplifier assembly stores this DTC if the malfunction has occurred for the period of time indicated in the brackets.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
- HINT:
-
If the ambient temperature is approximately -52.9°C (-63.22°F) or lower, DTC B1412 may be output even though the system is normal.
-
Click herePower Source / Network>NETWORKING>CAN COMMUNICATION SYSTEM>HOW TO PROCEED WITH TROUBLESHOOTING
PROCEDURE
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Body Electrical / Air Conditioner / Data List.
Check the value(s) by referring to the table below.
- Body Electrical > Air Conditioner > Data List
-
Tester Display Measurement Item Range Normal Condition Diagnostic Note Ambient Temp Sensor Thermistor assembly Min.: -23.30°C (-9.94°F)
Max.: 65.95°C (150.71°F)Actual ambient temperature displayed -
- Body Electrical > Air Conditioner > Data List
-
Tester Display Ambient Temp Sensor - 50003 121 2
- OK:
The display is as specified in the normal condition column.
- Result:
Result Proceed to NG A OK (When troubleshooting according to Problem Symptoms Table) B OK (When troubleshooting according to the DTC) C
A
B
C
| *a | Component without harness connected
(Thermistor Assembly) |
| *b | Sensing Portion |
| *c | Resistance (kΩ) |
| *d | Temperature (°C (°F)) |
| *e | Allowable Range |
Remove the thermistor assembly.
Click hereVehicle Interior>HEATING / AIR CONDITIONING>AMBIENT TEMPERATURE SENSOR>REMOVAL
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 1 - 2 15°C (59°F) 2.45 to 2.88 kΩ 1 - 2 20°C (68°F) 1.95 to 2.30 kΩ 1 - 2 25°C (77°F) 1.60 to 1.80 kΩ 1 - 2 30°C (86°F) 1.28 to 1.47 kΩ 1 - 2 35°C (95°F) 1.00 to 1.22 kΩ 1 - 2 40°C (104°F) 0.80 to 1.00 kΩ 1 - 2 45°C (113°F) 0.65 to 0.85 kΩ 1 - 2 50°C (122°F) 0.50 to 0.70 kΩ 1 - 2 55°C (131°F) 0.44 to 0.60 kΩ 1 - 2 60°C (140°F) 0.36 to 0.50 kΩ
- NOTICE:
- ·
Hold the sensor only by its connector. Touching the sensing portion may change the resistance value.
·When measuring, the sensor temperature must be the same as the ambient temperature.
- HINT:
-
As the temperature increases, the resistance decreases (see the graph).
- Result:
Proceed to OK NG
OK
NG
Disconnect the E43 combination meter assembly connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
Tester Connection Condition Specified Condition E43-35 (TX1+) - A17-2 Always Below 1 Ω E43-34 (TX1-) - A17-1 Always Below 1 Ω E43-35 (TX1+) - Body ground Always 10 kΩ or higher E43-34 (TX1-) - Body ground Always 10 kΩ or higher
- Result:
Proceed to OK NG
OK
NG
Replace the combination meter assembly.
Click hereVehicle Interior>METER / GAUGE / DISPLAY>COMBINATION METER>REMOVAL
- HINT:
-
Since the combination meter assembly cannot be inspected while it is removed from the vehicle, replace the combination meter assembly with a new or known good one and check that the condition returns to normal.
Check for DTCs.
- Body Electrical > Air Conditioner > Trouble Codes
- 50001 121
- Result:
Result Proceed to DTC B1412 is not output A DTC B1412 is output B
A
B