Dtc B1412/12 Ambient Temperature Sensor Circuit

Heater & Air Conditioning System. Toyota Rav4. Aca30, 33, 38 Gsa33 Zsa30, 35
Air Conditioning. Toyota Rav4. Aca30, 33, 38 Gsa33 Zsa30, 35

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

READ VALUE USING INTELLIGENT TESTER (AMBI TEMP SENS)

INSPECT AMBIENT TEMPERATURE SENSOR

CHECK WIRE HARNESS (AMBIENT TEMPERATURE SENSOR - COMBINATION METER)

DTC B1412/12 Ambient Temperature Sensor Circuit


DESCRIPTION

The ambient temperature sensor is installed in the front part of the condenser to detect the ambient temperature and control the air conditioner. The sensor is connected to the combination meter and 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 via the combination meter. 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 air conditioning amplifier applies a voltage (5 V) to the ambient temperature sensor and reads voltage changes as changes in the resistance of the ambient temperature sensor. The combination meter sends the read signal to the air conditioning amplifier via CAN communication.

DTC No.
DTC Detection Condition
Trouble Area
B1412/12
Open or short in ambient temperature sensor circuit
  1. Ambient temperature sensor
  2. Harness and connector between ambient temperature sensor and combination meter assembly
  3. Combination meter
  4. Air conditioning amplifier
  5. CAN communication line

WIRING DIAGRAM


Toyota Rav4. Aca30, 33, 38 Gsa33 Zsa30, 35.Air Conditioning.Air Conditioning System (For Automatic Air Conditioning System). Dtc B1412/12 Ambient Temperature Sensor Circuit


INSPECTION PROCEDURE

1.READ VALUE USING INTELLIGENT TESTER (AMBI TEMP SENS)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch on (IG) and turn the intelligent tester main switch ON.

  1. Select the item below in the Data List, and read the value displayed on the intelligent tester.

    Air conditioning amplifier:

    Item
    		Measurement Item / Display (Range)
    		Normal Condition
    		Diagnostic Note
    Ambi Temp Sens
    		Ambient temperature sensor /
    Min.: -23.3°C (-9.94°F)
    Max.: 65.95°C (150.71°F)
    		Actual ambient temperature is displayed
    		Open circuit: -23.3°C (-9.94°F)
    Short circuit: 65.95°C (150.71°F)
    OK:
    The display is as specified in the normal condition column.

    Result:

    Result
    		Proceed to
    NG
    		A
    OK (Checking from the PROBLEM SYMPTOMS TABLE)
    		B
    OK (Checking from the DTC)
    		C


B
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

C
REPLACE AIR CONDITIONING AMPLIFIER
A


2.INSPECT AMBIENT TEMPERATURE SENSOR
Toyota Rav4. Aca30, 33, 38 Gsa33 Zsa30, 35.Air Conditioning.Air Conditioning System (For Automatic Air Conditioning System). Dtc B1412/12 Ambient Temperature Sensor Circuit

  1. Remove the ambient temperature sensor.

  1. Measure the resistance of the sensor.

    Standard resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1 - 2
    		10°C (50°F)
    		3.00 to 3.73 kΩ
    1 - 2
    		15°C (50°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:
    1. Touching the sensor even slightly may change the resistance value. Be sure to hold the connector of the sensor.
    2. When measuring, the sensor temperature must be the same as the ambient temperature.
    HINT:
    As the temperature increases, the resistance decreases (see the graph).


NG
REPLACE AMBIENT TEMPERATURE SENSOR
OK


3.CHECK WIRE HARNESS (AMBIENT TEMPERATURE SENSOR - COMBINATION METER)
Toyota Rav4. Aca30, 33, 38 Gsa33 Zsa30, 35.Air Conditioning.Air Conditioning System (For Automatic Air Conditioning System). Dtc B1412/12 Ambient Temperature Sensor Circuit

  1. Disconnect the A24 sensor connector.

  1. Disconnect the E22 meter connector.

  1. Measure the resistance of the wire harness side connectors.

    Standard resistance:
    Tester Connection
    		Specified Condition
    A24-2 (OT+) - E22-23 (TEMP)
    		Below 1 Ω
    A24-1 (OT-) - E22-11 (TX1+)
    		Below 1 Ω
    A24-2 (OT+) - Body ground
    		1 MΩ or higher
    A24-1 (OT-) - Body ground
    		1 MΩ or higher


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

REPLACE COMBINATION METER