Toyota Venza manuals

Toyota Venza: Ambient Temperature Sensor Circuit (B1412/12)

Toyota Venza Service Manual / Heating / Air Conditioning / Air Conditioning System / Ambient Temperature Sensor Circuit (B1412/12)

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 A/C amplifier and detects fluctuations in the ambient temperature. This data is used for controlling the cabin temperature. The sensor sends a signal to the A/C amplifier. 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 A/C amplifier 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

  • Ambient temperature sensor
  • Harness or connector between ambient temperature sensor and A/C amplifier
  • A/C amplifier

WIRING DIAGRAM


PROCEDURE

1.

READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Body / Air Conditioner / Data List.

(e) 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

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


C

REPLACE A/C AMPLIFIER


A

2.

INSPECT AMBIENT TEMPERATURE SENSOR

(a) Remove the ambient temperature sensor.

(b) Disconnect the ambient temperature sensor connector.



(c) 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:

  • Hold the sensor only by 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 the graph).

Text in Illustration

*1

Component without harness connected

(Ambient Temperature Sensor)

*2

Sensing Portion


NG

REPLACE AMBIENT TEMPERATURE SENSOR


OK

3.

CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR - A/C AMPLIFIER)

(a) Disconnect the A/C amplifier connector.


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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D47-5 (TAM) - A4-2

Always

Below 1 Ω

D47-13 (GND) - A4-1

Always

Below 1 Ω

D47-5 (TAM) - Body ground

Always

10 kΩ or higher

D47-13 (GND) - Body ground

Always

10 kΩ or higher

Text in Illustration

*1

Front view of wire harness connector

(to A/C Amplifier)

*2

Front view of wire harness connector

(to Ambient Temperature Sensor)



OK

REPLACE A/C AMPLIFIER


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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