B1419

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

DTC B1419/19 - Rear Room Temperature Sensor Circuit

DESCRIPTION

The cooler (duct sensor) thermistor (rear room temperature sensor) is installed in the rear panel to detect the rear room temperature and control the heater and air conditioner AUTO mode. The resistance of the cooler (duct sensor) thermistor (rear room temperature sensor) changes in accordance with the rear room temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.
The air conditioning amplifier applies a voltage (5 V) to the cooler (duct sensor) thermistor (rear room temperature sensor) and reads voltage changes as changes in the resistance of the cooler (duct sensor) thermistor (rear room temperature sensor).





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM (ROOM TEMP SENSOR (REAR))
(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 / Air Conditioner / Data List / Rear Temp Sensor (Rear).
(e) According to the display on the Techstream, read the Data List.

Air Conditioner





OK:
The display is as specified in the normal condition.

Result





C -- REPLACE AIR CONDITIONING AMPLIFIER
B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
A -- Continue to next step.

2. INSPECT COOLER (DUCT SENSOR) THERMISTOR (REAR ROOM TEMPERATURE SENSOR)




(a) Remove the cooler (duct sensor) thermistor (rear room temperature sensor) Removal.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:





HINT:
- Touching the sensor even slightly 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.
- As the temperature increases, the resistance decreases (see the graph).

(c) Reinstall the cooler (duct sensor) thermistor (rear room temperature sensor).

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

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




(a) Disconnect the O15 cooler (duct sensor) thermistor (rear room temperature sensor) connector.
(b) Disconnect the H67 air conditioning amplifier connector.
(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





(d) Reconnect the air conditioning amplifier connector.
(e) Reconnect the cooler (duct sensor) thermistor (rear room temperature sensor) connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE AIR CONDITIONING AMPLIFIER