DTC    B1412/12    Ambient Temperature Sensor Circuit

for Preparation Click here


DESCRIPTION

The ambient temperature sensor is installed in front of the condenser. It detects the ambient temperature to control air conditioning AUTO mode. This sensor is connected to the air conditioning amplifier 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. 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 assembly applies voltage (5 V) to the ambient temperature sensor and reads voltage changes as the resistance of the ambient temperature sensor changes.

DTC No.
DTC Detection Condition
Trouble Area
B1412/12
Open or short in ambient temperature sensor circuit
  1. Ambient temperature sensor
  2. Harness or connector between ambient temperature sensor and air conditioning amplifier assembly
  3. Air conditioning amplifier assembly

WIRING DIAGRAM


E219965E03


INSPECTION PROCEDURE

HINT:
If the ambient temperature is approximately -52.9°C (-63.22°F) or lower, DTC B1412/12 may be output even though the system is normal.

1.READ VALUE USING INTELLIGENT TESTER

  1. Connect the intelligent tester to the DLC3.

  1. Turn the power switch on (IG).

  1. Turn the intelligent tester on.

  1. Enter the following menus: Body / Air Conditioner / Data List.

  1. Check the value(s) by referring to the table below.

    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
    		-

    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



B
PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE (Click here)

C
REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY (Click here)
A


2.INSPECT AMBIENT TEMPERATURE SENSOR

  1. Remove the ambient temperature sensor.



    E214922E09

  1. Disconnect the A4 ambient temperature sensor connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    A4-1 - A4-2
    		10°C (50°F)
    		3.00 to 3.73 kΩ
    A4-1 - A4-2
    		15°C (59°F)
    		2.45 to 2.88 kΩ
    A4-1 - A4-2
    		20°C (68°F)
    		1.95 to 2.30 kΩ
    A4-1 - A4-2
    		25°C (77°F)
    		1.60 to 1.80 kΩ
    A4-1 - A4-2
    		30°C (86°F)
    		1.28 to 1.47 kΩ
    A4-1 - A4-2
    		35°C (95°F)
    		1.00 to 1.22 kΩ
    A4-1 - A4-2
    		40°C (104°F)
    		0.80 to 1.00 kΩ
    A4-1 - A4-2
    		45°C (113°F)
    		0.65 to 0.85 kΩ
    A4-1 - A4-2
    		50°C (122°F)
    		0.50 to 0.70 kΩ
    A4-1 - A4-2
    		55°C (131°F)
    		0.44 to 0.60 kΩ
    A4-1 - A4-2
    		60°C (140°F)
    		0.36 to 0.50 kΩ

    NOTICE:
    1. Hold the sensor only by its connector. Touching the sensor may change the resistance value.
    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).

    Text in Illustration 
    *a
    		Component without harness connected
    (Ambient Temperature Sensor)
    *b
    		Sensing Portion
    *c
    		Resistance (kΩ)
    *d
    		Allowable Range
    *e
    		Temperature (°C (°F))



NG
REPLACE AMBIENT TEMPERATURE SENSOR (Click here)
OK


3.CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR - AIR CONDITIONING AMPLIFIER)

  1. Disconnect the H85 air conditioning amplifier assembly connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    H85-5 (TAM) - A4-1
    		Always
    		Below 1 Ω
    H85-13 (SG-2) - A4-2
    		Always
    		Below 1 Ω
    H85-5 (TAM) - Body ground
    		Always
    		10 kΩ or higher
    H85-13 (SG-2) - Body ground
    		Always
    		10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY (Click here)