B1412

HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1412/12: Ambient Temperature Sensor Circuit
B1412/12 - Ambient Temperature Sensor Circuit

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 connected to the ECM 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 via the ECM. 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 ECM applies voltage (5 V) to the ambient temperature sensor and reads voltage changes as the resistance of the ambient temperature sensor changes. The ECM sends the signal to the A/C amplifier via CAN and body multiplex communication.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK MULTIPLEX COMMUNICATION SYSTEM

(a) Use the Techstream to check if the Multiplex Communication System (MPX) is functioning normally.

Result:





B -- GO TO MULTIPLEX COMMUNICATION SYSTEM
A -- Continue to next step.

2. CHECK CAN COMMUNICATION SYSTEM

(a) Use the Techstream to check if the CAN Communication System is functioning normally.

Result:





B -- GO TO CAN COMMUNICATION SYSTEM
A -- Continue to next step.

3. READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(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





OK:

The display is as specified in the normal condition column.

Result:





B -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures

C -- REPLACE A/C AMPLIFIER Removal
A -- Continue to next step.

4. 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:





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





NG -- REPLACE AMBIENT TEMPERATURE SENSOR Removal
OK -- Continue to next step.

5. CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR - ECM)

(a) Disconnect the ECM connector.









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





Standard Resistance:





*1: for 2GR-FSE

*2: for 4GR-FSE

Text in Illustration





Result:





B -- REPLACE ECM (for 4GR-FSE) Removal

C -- REPAIR OR REPLACE HARNESS OR CONNECTOR

A -- REPLACE ECM (for 2GR-FSE) Removal