DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
READ VALUE USING INTELLIGENT TESTER (AMBIENT TEMP SENSOR)
INSPECT COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR)
CHECK HARNESS AND CONNECTOR (COOLER THERMISTOR - AIR CONDITIONING AMPLIFIER)
DTC B1412 Ambient Temperature Sensor Circuit
DESCRIPTION
The cooler thermistor (ambient temperature sensor) is installed in the front part of the cooler condenser assembly. This sensor is connected to the air conditioning amplifier assembly and detects fluctuations in the ambient temperature. The sensor sends a signal to the air conditioning amplifier assembly. The resistance of the cooler thermistor (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 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).
| DTC Code | DTC Detection Condition | Trouble Area |
| B1412 |
An open or short in the cooler thermistor (ambient temperature sensor) circuit is detected for 8.5 minutes or more. |
Cooler thermistor (ambient temperature sensor)
Harness or connector
Air conditioning amplifier assembly
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WIRING DIAGRAM
INSPECTION PROCEDURE
| 1.READ VALUE USING INTELLIGENT TESTER (AMBIENT TEMP SENSOR) |
Use the Data List to check if the cooler thermistor (ambient temperature sensor) is functioning properly ().
Air Conditioner| Tester Display | Measurement Item/Range | Normal Condition | Diagnostic Note |
| Ambient Temp Sensor |
Cooler thermistor (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.
Result| Result | Proceed to |
| OK (When troubleshooting according to problem symptoms table) | A |
| OK (When troubleshooting according to the DTC) | B |
| NG | C |
| | REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY ()
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| A | |
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| PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE ()
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| 2.INSPECT COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR) |
Remove the cooler thermistor (ambient temperature sensor) ().
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 |
Text in Illustration| *a | Sensing Portion |
| *b | Resistance |
| *c | Allowable Range |
| *d | Temperature |
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.
- As the temperature increases, the resistance decreases (refer to the graph).
| | REPLACE COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR) ()
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| 3.CHECK HARNESS AND CONNECTOR (COOLER THERMISTOR - AIR CONDITIONING AMPLIFIER) |
Disconnect the A14 cooler thermistor (ambient temperature sensor) connector.
Disconnect the E81 air conditioning amplifier assembly connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
| Tester Connection | Condition | Specified Condition |
| A14-1 - E81-5 (TAM) | Always | Below 1 Ω |
| A14-2 - E81-13 (SG-2) |
| E81-5 (TAM) - Body ground | Always | 10 kΩ or higher |
| E81-13 (SG-2) - Body ground |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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| OK | |
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| REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY ()
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