B1431

AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1431: Air Mix Damper Position Sensor Circuit (Passenger Side)

DTC B1431 - Air Mix Damper Position Sensor Circuit (Passenger Side)

DESCRIPTION

This sensor detects the position of the air mix control servo motor (air mix damper) and sends the appropriate signals to the air conditioning amplifier. The position sensor is built into the air mix control servo motor. The position sensor resistance changes as the air mix control servo motor arm moves.
It outputs voltage (5 V) that is input to terminal 1 (VZ) and terminal 3 (PT) via the variable resistor, and then to the air conditioning amplifier. The air conditioning amplifier reads the arm position with the input voltage from the position sensor.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM
(a) Connect Techstream to DLC3.
(b) Turn the power switch ON (IG) and turn Techstream ON.
(c) Select the item below in the Data List, and read the display on Techstream.

Air conditioning amplifier

OK:
The displayed 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. CHECK AIR CONDITIONING AMPLIFIER (TP VOLTAGE)

(a) Remove the air conditioning amplifier with its connectors still connected.
(b) Change the set temperature to activate the air mix servo motor.
(c) Measure the voltage of the wire harness side connector.
Standard voltage:

HINT: As the set temperature increases, the voltage decreases gradually without interruption.

Result

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

3. INSPECT AIR MIX CONTROL SERVO MOTOR

(a) Remove the air mix control servo motor.
(b) Measure the resistance of the servo motor.
Standard resistance:

HINT:
- Refer to the operation procedure for air mix control servo motor B1441.
- As the air mix control servo motor moves from the COOL position to HOT position, the resistance decreases gradually without interruption.

NG -- REPLACE AIR MIX CONTROL SERVO MOTOR
OK -- Continue to next step.

4. CHECK WIRE HARNESS (AIR MIX CONTROL SERVO MOTOR - AIR CONDITIONING AMPLIFIER)

(a) Disconnect the A15 servo connector.
(b) Disconnect the A7 amplifier connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:

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