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DTC 19





HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1419/19: Rear Room Temperature Sensor Circuit
B1419/19 - Rear Room Temperature Sensor Circuit

DESCRIPTION

The cooler thermistor (rear room temperature sensor) is installed in the rear panel. It detects the rear cabin temperature to control the air conditioning AUTO mode. The resistance of the cooler thermistor (rear room temperature sensor) changes in accordance with the rear cabin 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 cooler thermistor (rear room temperature sensor) and reads voltage changes as the resistance of the cooler thermistor (rear room temperature sensor) changes.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM (REAR ROOM TEMPERATURE SENSOR)

(a) Use the Data List to check if the rear room temperature sensor is functioning properly Scan Tool Testing and Procedures.

Air Conditioner





OK:

The display is as specified in the normal condition column.

Result





C -- INSPECT COOLER THERMISTOR (REAR ROOM TEMPERATURE SENSOR)

B -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

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

2. INSPECT COOLER THERMISTOR (REAR ROOM TEMPERATURE SENSOR)

(a) Remove the cooler thermistor (rear room temperature sensor) Removal.





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

Standard Resistance:





Text in Illustration





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 (refer to the graph).

NG -- REPLACE COOLER THERMISTOR (REAR ROOM TEMPERATURE SENSOR) Removal
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (REAR ROOM TEMPERATURE SENSOR - AIR CONDITIONING AMPLIFIER)

(a) Disconnect the G12 amplifier connector.

(b) Disconnect the Q21 sensor connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal