Toyota 4Runner: Air Mix Damper Control Servo Motor Circuit (Driver Side) (B1446/46)

Toyota 4Runner Service Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System(for Automatic Air Conditioning System) / Air Mix Damper Control Servo Motor Circuit (Driver Side) (B1446/46)

DESCRIPTION

The damper servo sub-assembly (driver side air mix damper servo) sends pulse signals to inform the No. 1 air conditioning amplifier assembly of the damper position. The No. 1 air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the air mix damper (for driver side) to any position. As a result, the air mix damper (for driver side) varies the mixture of hot air from the heater core and cold air from the evaporator so that the temperature of the air blowing toward the front passenger side is as requested.

HINT:

Confirm that no mechanical problem is present because this trouble code may be stored when either a damper link or damper is mechanically locked.

DTC Code	DTC Detection Condition	Trouble Area
B1446/46	The air mix damper position does not change when the No. 1 air conditioning amplifier assembly operates the damper servo sub-assembly (driver side air mix damper servo).	Damper servo sub-assembly (driver side air mix damper servo) Air conditioning harness assembly No. 1 air conditioning amplifier assembly

WIRING DIAGRAM

PROCEDURE

1.	READ VALUE USING TECHSTREAM (DRIVER SIDE AIR MIX DAMPER SERVO)

(a) Use the Data List to check if the damper servo sub-assembly (driver side air mix damper servo) is functioning properly (See page ).

Air Conditioner

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
Air Mix Servo Targ Pulse (D)	Damper servo sub-assembly (driver side air mix damper servo) target pulse / Min.: 0, Max.: 255	107 (pulse): MAX COOL 26 (pulse): MAX HOT	-
Air Mix Servo Actual Pulse (D)	Damper servo sub-assembly (driver side air mix damper servo) actual pulse / Min.: 0, Max.: 255	107 (pulse): MAX COOL 26 (pulse): MAX HOT	-

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Air Mix Servo Targ Pulse (D)

Damper servo sub-assembly (driver side air mix damper servo) target pulse / Min.: 0, Max.: 255

107 (pulse): MAX COOL

26 (pulse): MAX HOT

Air Mix Servo Actual Pulse (D)

Damper servo sub-assembly (driver side air mix damper servo) actual pulse / Min.: 0, Max.: 255

107 (pulse): MAX COOL

26 (pulse): MAX HOT

OK:

The display is as specified in the normal condition column.

Result

Result	Proceed to
OK (When troubleshooting according to problem symptoms table)	A
OK (When troubleshooting according to the DTC)	B
NG	C

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

REPLACE NO. 1 AIR CONDITIONING AMPLIFIER ASSEMBLY

2.	PERFORM ACTIVE TEST USING TECHSTREAM (DRIVER SIDE AIR MIX DAMPER SERVO)

(a) Select the Active Test, use the Techstream to generate a control command, and then check that the damper servo sub-assembly (driver side air mix damper servo) operates (See page ).

Air Conditioner

Tester Display	Test Part	Control Range	Diagnostic Note
Air Mix Servo Targ Pulse (D)	Damper servo sub-assembly (driver side air mix damper servo) target pulse	Min.: 0, Max.: 255	-

OK:

Damper servo sub-assembly (driver side air mix damper servo) operates normally.

REPLACE NO. 1 AIR CONDITIONING AMPLIFIER ASSEMBLY

3.	REPLACE DAMPER SERVO SUB-ASSEMBLY (DRIVER SIDE AIR MIX DAMPER SERVO)

(a) Replace the damper servo sub-assembly (driver side air mix damper servo) (See page ).

HINT:

Since the damper servo sub-assembly (driver side air mix damper servo) cannot be inspected while it is removed from the vehicle, replace the damper servo sub-assembly (driver side air mix damper servo) with a new or normally functioning one.

4.	CHECK FOR DTC

(a) Clear the DTCs (See page ).

(b) Check for DTCs (See page ).

OK:

DTC B1446 is not output.

END (DAMPER SERVO SUB-ASSEMBLY [DRIVER SIDE AIR MIX DAMPER SERVO] IS FAULTY)

5.	REPLACE NO. 1 AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Temporarily replace the No. 1 air conditioning amplifier assembly with a new or normally functioning one (See page ).

6.	CHECK FOR DTC

(a) Clear the DTCs (See page ).

(b) Check for DTCs (See page ).

OK:

DTC B1446 is not output.

END (NO. 1 AIR CONDITIONING AMPLIFIER ASSEMBLY)

REPLACE AIR CONDITIONING HARNESS ASSEMBLY

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BUS IC Communication Malfunction (B1497/97)

DESCRIPTION The air conditioning harness assembly connects the No. 1 air conditioning amplifier assembly and each servo motor. The No. 1 air conditioning amplifier assembly supplies power and sen ...

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