HEATING / AIR CONDITIONING AIR CONDITIONING SYSTEM(for Heater System) B1412 Ambient Temperature Sensor Circuit
DESCRIPTION
The thermistor assembly (ambient temperature sensor) is installed near the hood courtesy 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 air conditioning amplifier assembly via CAN communication. The resistance of the thermistor assembly (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 air conditioning amplifier assembly applies voltage (3.3 V) to the thermistor assembly (ambient temperature sensor) and reads voltage changes due to changes in the resistance of the thermistor assembly (ambient temperature sensor).
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | Memory |
|---|---|---|---|---|
| B1412 | Ambient Temperature Sensor Circuit | ·
Diagnosis condition: None ·
Malfunction status: Open or short in ambient temperature sensor circuit ·
Detection time: None (Present malfunction), continuously for 4 seconds or more (Past malfunction) |
·
Thermistor assembly (ambient temperature sensor) ·
Harness or connector ·
Combination meter assembly |
Memorized |
- 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.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
- NOTICE:
-
When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.
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.
Read the Data List according to the display on the GTS.
- Body Electrical > Air Conditioner > Data List
-
Tester Display Measurement Item Range Normal Condition Diagnostic Note Ambient Temp Sensor Thermistor assembly (ambient temperature sensor) Min.: -23.30°C (-9.94°F)
Max.: 65.95°C (150.71°F)Actual ambient temperature displayed Thermistor assembly (ambient temperature sensor) circuit malfunction
·When open circuit: -23.30°C (-9.94°F)
·When short circuit: 65.95°C (150.71°F)
- 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:
Proceed to OK NG
OK
NG
Remove the thermistor assembly (ambient temperature sensor).
Inspect the thermistor assembly (ambient temperature sensor).
- Result:
Proceed to OK NG
OK
NG
Disconnect the N22 combination meter assembly connector.
Disconnect the A36 thermistor assembly (ambient temperature sensor) connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
Tester Connection Condition Specified Condition N22-33 (TX1+) - A36-2 Always Below 1 Ω N22-26 (TX1-) - A36-1 Always Below 1 Ω N22-33 (TX1+) or A36-2 - Other terminals and body ground Always 10 kΩ or higher N22-26 (TX1-) or A36-1 - Other terminals and body ground Always 10 kΩ or higher
- Result:
Proceed to OK NG
OK
NG