B1412

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

DESCRIPTION

The sensor connected to the engine room J/B assembly (front controller) detects fluctuations in the ambient temperature that is used for controlling the interior temperature. The sensor sends a to the A/C amplifier via the engine room J/B assembly (front controller).





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM

(a) Connect Techstream to the DLC3.

(b) Turn the ignition switch on (IG) and turn Techstream on.

(c) Select the item below in the Data List, and read the display on Techstream.

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 ENGINE ROOM JUNCTION BLOCK ASSEMBLY (FRONT CONTROLLER)

(a) Remove the engine room J/B assembly (front controller) with connectors still connected.





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

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

Standard Voltage:





HINT
As the temperature increases, the voltage decreases.

Result:





C -- REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY (FRONT CONTROLLER)

B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
A -- Continue to next step.

3. INSPECT A/C AMBIENT TEMPERATURE SENSOR

(a) Remove the A/C ambient temperature sensor.





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





Standard Resistance:





NOTICE:
* Only hold the sensor at 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).

NG -- REPLACE A/C AMBIENT TEMPERATURE SENSOR
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (ENGINE ROOM J/B ASSEMBLY - A/C AMBIENT TEMPERATURE SENSOR)

(a) Disconnect the connector from A/C ambient temperature sensor.





(b) Disconnect the connector from the engine room J/B assembly.





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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

5. CHECK HARNESS AND CONNECTOR (ENGINE ROOM J/B ASSEMBLY (FRONT CONTROLLER) - BODY GROUND)

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





Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

6. REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY (FRONT CONTROLLER)

HINT
Check for DTC B1412/12 after replacing the engine room J/B assembly.

OK:

DTC B1412/12 is not output.

NG -- REPLACE AIR CONDITIONING AMPLIFIER

OK -- END