B1412

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

DESCRIPTION

The ambient temperature sensor (thermistor assembly) is installed in the front part of the condenser to detect the ambient temperature and control the air conditioner. The sensor is connected to the combination meter assembly and detects fluctuations in the ambient temperature. This data is used for controlling the room temperature. The sensor sends a signal to the air conditioning amplifier via the combination meter 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 combination meter assembly applies a voltage (5 V) to the ambient temperature sensor (thermistor assembly) and reads voltage changes as changes in the resistance of the ambient temperature sensor (thermistor assembly). The combination meter assembly sends the read signal to the air conditioning amplifier via CAN communications.





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
Before performing the inspection, check that there are no problems related to the CAN communication system.

PROCEDURE

1. READ VALUE USING TECHSTREAM (AMBIENT TEMPERATURE SENSOR)

(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 / Combination Meter / Data List.

(e) According to the display on the Techstream, read the Data List.

Combination Meter





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 COMBINATION METER ASSEMBLY
A -- Continue to next step.

2. INSPECT AMBIENT TEMPERATURE SENSOR (THERMISTOR ASSEMBLY)

(a) Inspect the ambient temperature sensor (thermistor assembly) Testing and Inspection.

NG -- REPLACE AMBIENT TEMPERATURE SENSOR (THERMISTOR ASSEMBLY) Removal
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - AMBIENT TEMPERATURE SENSOR)

(a) Disconnect the D1 combination meter assembly connector.

(b) Disconnect the A25 ambient temperature sensor (thermistor assembly) connector.

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

Standard Resistance:





(d) Reconnect the ambient temperature sensor (thermistor assembly) connector.

(e) Reconnect the combination meter assembly connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE COMBINATION METER ASSEMBLY Removal

4. REPLACE COMBINATION METER ASSEMBLY

(a) Replace the combination meter assembly Removal.

HINT
Since the combination meter assembly cannot be inspected while it is removed from the vehicle, replace the combination meter assembly with a normal one and check that the condition returns to normal.

NEXT -- Continue to next step.

5. CHECK FOR DTC

(a) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.

(b) Check for DTCs Reading and Clearing Diagnostic Trouble Codes.

Result





B -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

A -- END