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

Toyota Tacoma 2015-2018 Service Manual / Air Conditioning / Air Conditioning System(for Manual Air Conditioning System) / 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

1.	READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to 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	-

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

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

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 ).

REPLACE AMBIENT TEMPERATURE SENSOR

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.

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

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR

Diagnostic Trouble Code Chart

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