Ambient Temperature Display System [08/2020 - ]: Procedure

1. Clear the DTCs.

   Refer to DTC CHECK / CLEAR [02/2019 - ]

   Body Electrical > Air Conditioner > Clear DTCs 

2. Check for DTCs when the following conditions are met.

   Refer to DTC CHECK / CLEAR [02/2019 - ]

   Body Electrical > Air Conditioner > Trouble Codes 

   NOTE:

   During the parked vehicle inspection, perform the inspection with the ignition switch ON (do not start the engine and electric motor).

   Result

   Result	Proceed to
   DTC B1412 is not output	A
   DTC B1412 is output	B

Result: 

B 

GO TO DTC B1412. Refer to  DTC B1412: Ambient Temperature Sensor Circuit [02/2019 - ] 

Result: 

A 

See step  2

1. Disconnect the thermistor assembly (ambient temperature sensor) connector.
2. Measure the resistance according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component without harness connected (Thermistor Assembly [Ambient Temperature Sensor])
   *b	Sensing Portion
   *c	Resistance (kΩ)
   *d	Temperature (°C [°F])
   *e	Allowable Range

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A19-1 - A19-2	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

   NOTE:

   • Hold the sensor only by its connector. Touching the sensing portion may change the resistance value.
   • When measuring, the sensor temperature must be the same as the ambient temperature.
   • Use a thermometer to detect the ambient temperature of the installation area around the thermistor assembly (ambient temperature sensor).

   HINT: 

   As the temperature increases, the resistance decreases (see the graph).

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE THERMISTOR ASSEMBLY (AMBIENT TEMPERATURE SENSOR). Refer to  REMOVAL [11/2018 - ] 

Result: 

OK 

See step  3

1. Disconnect the G47 air conditioning amplifier assembly connector.
2. Disconnect the A19 thermistor assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   G47-1 (TAM) - A19-2	Always	Below 1 Ω
   G47-14 (SG-2) - A19-1	Always	Below 1 Ω
   G47-1 (TAM) or A19-2 - Other terminals and body ground	Always	10 kΩ or higher
   G47-14 (SG-2) or A19-1 - Other terminals and body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Disconnect the cable from the negative (-) auxiliary battery terminal.
   NOTE:

   Make sure the wire harness(es) and connector(s) for the vehicle being inspected are connected. After the ignition switch is turned off, the navigation system or audio and visual system stores the various memory and settings within approximately 6 minutes. Therefore, make sure to disconnect the cable from the negative (-) auxiliary battery terminal after confirming that 6 minutes or more have elapsed since turning the ignition switch off.

2. Disconnect the cable from the negative (-) auxiliary battery terminal and wait 90 seconds or more.

   HINT: 

   The air conditioning amplifier assembly reads and memorizes the thermistor assembly (ambient temperature sensor) detection value (THO) from before the ignition switch was turned off for 1 hour after turning the ignition switch off. Therefore, it is necessary to switch off the air conditioning amplifier assembly internal power source and clear the stored values from before the ignition switch was turned off.

3. Connect the cable to the negative (-) auxiliary battery terminal.
4. Using a thermometer, measure the ambient temperature of the installation area around the thermistor assembly (ambient temperature sensor) and record it.
   NOTE:

   • During the parked vehicle inspection, perform the inspection with the ignition switch ON (do not start the engine and electric motor).
   • Set the thermometer so that the measuring tip is at approximately the same height and lateral position as the thermistor assembly (ambient temperature sensor) installed behind the front grille and approximately 50 mm (1.97 in.) from the surface of the front grille, and then maintain the thermometer in that position.
   • After the ignition switch is turned to ON, the ambient temperature, detected signal value and sensing portion temperature of the thermistor assembly (ambient temperature sensor) and the measuring tip of the thermometer will equalize. Therefore, make sure to wait approximately 6 minutes before measuring.
   • If the temperature sensing portion of the thermistor assembly (ambient temperature sensor) is touched, the body temperature of the technician may cause an incorrect temperature measurement. Therefore, do not touch the temperature sensor when measuring the ambient temperature of the installation area around the thermistor assembly (ambient temperature sensor).
   • Do not move the thermometer from the maintained position, touch the measuring tip or allow it to contact the front grille.
5. Record the ambient temperature value displayed on the multi-information display of the combination meter assembly.
6. Compare the ambient temperature of the installation area around the thermistor assembly (ambient temperature sensor) with the ambient temperature value displayed on the multi-information display of the combination meter assembly.

   Standard

   The ambient temperature of the installation area around the thermistor assembly (ambient temperature sensor) is approximately the same as the ambient temperature value displayed on the multi-information display of the combination meter assembly.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

END 

Result: 

NG 

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [11/2018 - ]