Toyota Venza: Air Mix Damper Control Servo Motor Circuit (Driver Side) (B1446/46)

Toyota Venza Service Manual / Heating / Air Conditioning / Air Conditioning System / Air Mix Damper Control Servo Motor Circuit (Driver Side) (B1446/46)

DESCRIPTION

The air mix control servo motor sends pulse signals to indicate the damper position to the A/C amplifier. The A/C amplifier activates the motor (normal or reverse) based on these signals to move the air mix damper (driver side) to any position. As a result, the amount of air passing through the heater core after passing through the evaporator is adjusted, and the temperature of the air blowing toward the driver side is controlled.

The A/C amplifier communicates with the servo through a communication/driver IC and wiring assembly called the air conditioning harness.

HINT:

Confirm that no mechanical problem is present because this DTC can be output when either a damper link or the damper is mechanically locked.

DTC No.	DTC Detection Condition	Trouble Area
B1446/46	Air mix damper position sensor value does not change even if A/C amplifier operates air mix control servo motor	No. 1 air mix control servo motor (air mix control servo motor) Air conditioning harness A/C amplifier

WIRING DIAGRAM

PROCEDURE

1.	READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Operate the driver side temperature adjustment switch.

(e) Enter the following menus: Body / Air Conditioner / Data List.

(f) Check the value(s) by referring to the table below.

Air Conditioner

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
Air Mix Servo Targ Pulse (D)	Driver side air mix servo motor target pulse / Min.: 0, Max.: 255	MAX. COLD: 5 (pulse) MAX. HOT: 103 (pulse)	-

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Air Mix Servo Targ Pulse (D)

Driver side air mix servo motor target pulse / Min.: 0, Max.: 255

MAX. COLD: 5 (pulse)

MAX. HOT: 103 (pulse)

OK:

The display is as specified in the Normal Condition column.

Result	Proceed to
NG	A
OK (When troubleshooting according to Problem Symptoms Table)	B
OK (When troubleshooting according to the DTC)	C

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

REPLACE A/C AMPLIFIER

2.	PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Enter the following menus: Body / Air Conditioner / Active Test.

(e) Check the operation by referring to the table below.

Air Conditioner

Tester Display	Test Part	Control Range	Diagnostic Note
Air Mix Servo Targ Pulse (D)	Air mix servo motor pulse (D side)	Min.: 0, Max.: 255	-

OK:

Air temperature changes in accordance with each control range.

REPLACE A/C AMPLIFIER

3.	INSPECT AIR MIX CONTROL SERVO MOTOR

(a) Replace the No. 1 air mix control servo motor (air mix control servo motor) (See page ).

HINT:

Since the servo motor cannot be inspected while it is removed from the vehicle, replace the servo motor with a new or a known good one and check that the condition returns to normal.

(b) Check for the DTC.

Result	Proceed to
DTC B1446/46 is output	A
DTC B1446/46 is not output	B

REPLACE AIR MIX CONTROL SERVO MOTOR

4.	INSPECT AIR CONDITIONING HARNESS

(a) Replace the air conditioning harness (See page ).

HINT:

Since the air conditioning harness cannot be inspected while it is removed from the vehicle, replace the air conditioning harness with a new or a known good one and check that the condition returns to normal.

(b) Check for the DTC.

Result	Proceed to
DTC B1446/46 is output	A
DTC B1446/46 is not output	B

REPLACE A/C AMPLIFIER

REPLACE AIR CONDITIONING HARNESS

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