DTC B1412/12: Ambient Temperature Sensor Circuit: Procedure

1. Connect Techstream to the DLC3.
2. Turn the ignition switch on (IG) and turn Techstream on.
3. Select the item below in the Data List, and read the display on Techstream.
   DATA LIST / AIR CONDITIONER:
   
   

   Item	Measurement Item / Display (Range)	Normal Condition	Diagnostic Note
   Ambient Temp Sensor	Ambient temperature sensor / min.: -23.3°C (-9.94°F) max.: 65.96°C (150.71°F)	Actual ambient temperature is displayed	-

   OK

   The display is as specified in the normal condition.

   Result

   Result	Proceed to
   NG	A
   OK (Checking from the PROBLEM SYMPTOM 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: Go to next step 

1. Remove the engine room J/B assembly (front controller) with connectors still connected.
   Fig 1: Identifying Engine Room J/B Assembly Connector Wire Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Turn the ignition switch on (IG).
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   1I-4 - 1I-5	Ignition switch on (IG) at 25°C (77°F)	1.8 to 2.2 V
   1I-4 - 1I-5	Ignition switch on (IG) at 40°C (104°F)	1.2 to 1.6 V

   HINT: 

   As the temperature increases, the voltage decreases.

   Result

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

B → PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN  PROBLEM SYMPTOMS TABLE 

C → See step   6 

A: Go to next step 

1. Remove the A/C ambient temperature sensor.
   Fig 2: Identifying A11 A/C Ambient Temperature Sensor Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistant according to the value(s) in the table below.
   Fig 3: Identifying Resistance Graph

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A11-1 - A11-2	10°C (50°F)	3.00 to 3.73 kΩ
   A11-1 - A11-2	15°C (59°F)	2.45 to 2.88 kΩ
   A11-1 - A11-2	20°C (68°F)	1.95 to 2.30 kΩ
   A11-1 - A11-2	25°C (77°F)	1.60 to 1.80 kΩ
   A11-1 - A11-2	30°C (86°F)	1.28 to 1.47 kΩ
   A11-1 - A11-2	35°C (95°F)	1.00 to 1.22 kΩ
   A11-1 - A11-2	40°C (104°F)	0.80 to 1.00 kΩ
   A11-1 - A11-2	45°C (113°F)	0.65 to 0.85 kΩ
   A11-1 - A11-2	50°C (122°F)	0.50 to 0.70 kΩ
   A11-1 - A11-2	55°C (131°F)	0.44 to 0.60 kΩ
   A11-1 - A11-2	60°C (140°F)	0.36 to 0.50 kΩ

   NOTE:

   • Only hold the sensor at its connector. Touching the sensor 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 b the graph).

NG → REPLACE A/C AMBIENT TEMPERATURE SENSOR 

OK: Go to next step 

1. Disconnect the connector from A/C ambient temperature sensor.
   Fig 4: Identifying A/C Ambient Temperature Sensor Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the connector from the engine room J/B assembly.
   Fig 5: Identifying Engine Room J/B Assembly Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   1I-5 - A11-1	Always	Below 1 Ω
   1I-4 - A11-2	Always	Below 1 Ω
   1I-5 - Body ground	Always	10 kΩ or higher
   1I-4 - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Measure the resistance according to the value(s) in the table below.
   Fig 6: Identifying 1H Engine Room J/B Assembly Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   1H-8 - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

HINT: 

Check for DTC B1412/12 after replacing the engine room J/B assembly.

OK

DTC B1412/12 is not output.

NG → REPLACE AIR CONDITIONING AMPLIFIER 

OK → END