Toyota Tacoma manuals

Toyota Tacoma 2015-2018 Service Manual: Ambient Temperature Sensor Circuit (B1412)

DESCRIPTION

The ambient temperature sensor is installed in front of the condenser to detect the ambient temperature which is used to control the air conditioning system 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 a voltage (5 V) to the ambient temperature sensor and reads voltage changes due to changes in the resistance of the ambient temperature sensor.

DTC No.

DTC Detection Condition

Trouble Area

B1412

Open or short in cooler thermistor (ambient temperature sensor) circuit

  • Ambient temperature sensor
  • Harness or connector
  • Air conditioning amplifier assembly

WIRING DIAGRAM

PROCEDURE

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 Electrical / 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: -23.30°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 AIR CONDITIONING AMPLIFIER ASSEMBLY

A

2.

INSPECT AMBIENT TEMPERATURE SENSOR

(a) Remove the ambient temperature sensor (See page (b) Inspect the ambient temperature sensor (See page ).

(b) Inspect the ambient temperature sensor (See page ).

NG

REPLACE AMBIENT TEMPERATURE SENSOR

OK

3.

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

(a) Disconnect the A13 ambient temperature sensor connector.

(b) Disconnect the A14 air conditioning amplifier assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A14-7 (TAM) - A13-1 (+)

Always

Below 1 Ω

A14-33 (SG-1) - A13-2 (-)

Always

Below 1 Ω

A14-7 (TAM) or A13-1 (+) - Body ground

Always

10 kΩ or higher

A14-33 (SG-1) or A13-2 (-) - Body ground

Always

10 kΩ or higher

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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