Toyota Tundra Service Manual: Ambient Temperature Sensor Circuit (B1412/12)

DESCRIPTION

The ambient temperature sensor is installed in front of the condenser to detect the ambient temperature which is used to control the air conditioner "AUTO" mode. This sensor is connected to the air conditioning amplifier 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. 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 applies voltage (5 V) to the ambient temperature sensor and reads voltage changes as the resistance of the ambient temperature sensor changes.

WIRING DIAGRAM

PROCEDURE

(a) Use the Data List to check if the ambient temperature sensor is functioning properly.

OK:

The display is as specified in the normal condition.

B

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

C

REPLACE AIR CONDITIONING AMPLIFIER

A

(a) Remove the ambient temperature sensor (see page ).

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

Standard resistance:

NOTICE:

• Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
• When measuring, the sensor temperature must be the same as the ambient temperature.

HINT:

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

NG

REPLACE AMBIENT TEMPERATURE SENSOR

OK

(a) Disconnect the A15 sensor connector.

(b) Disconnect the J19 air conditioning amplifier connector.

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

Standard resistance:

OK

REPLACE AIR CONDITIONING AMPLIFIER

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR