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

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

DESCRIPTION

The No. 1 damper servo sub-assembly (air mix damper servo motor [for driver side]) sends pulse signals to inform the air conditioning amplifier of the damper position. The air conditioning amplifier activates the motor (normal, reverse) based on the signals to move the air mix damper (for driver side) to any position. As a result the amount of air that has passed through the evaporator and is now passing through the heater core is adjusted, and the temperature of the air blowing toward the driver side is controlled.

HINT:

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

DTC Code	DTC Detection Condition	Trouble Area
B1446/46	Air mix damper position sensor value does not change even if air conditioning amplifier operates No. 1 damper servo sub-assembly (air mix damper servo motor [for driver side])	No. 1 damper servo sub-assembly (air mix damper servo motor [for driver side]) Air conditioning harness Air conditioning amplifier

WIRING DIAGRAM

PROCEDURE

1.	READ VALUE USING TECHSTREAM (AIR MIX SERVO MOTOR TARGET PULSE (for Driver Side))

(a) Use the Data List to check if the servo motor is functioning properly.

Air Conditioner

Tester Display

Measurement Item / Range

Normal Condition

Diagnostic Note

Air Mix Servo Targ Pulse (D)

No. 1 damper servo sub-assembly (air mix damper servo motor [for driver side]) target pulse /

Min.: 0, Max.: 255

MAX. COLD: 5 (pulse)

MAX. HOT: 104 (pulse)

OK:

The display is as specified in the normal condition.

Result

Result	Proceed to
OK (Checking from the DTC)	A
OK (Checking from the PROBLEM SYMPTOMS TABLE)	B
NG	C

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

REPLACE AIR CONDITIONING AMPLIFIER

2.	REPLACE NO. 1 DAMPER SERVO SUB-ASSEMBLY (AIR MIX SERVO MOTOR [for Driver Side])

(a) Temporarily replace the No. 1 damper servo sub-assembly (air mix damper servo motor [for driver side]) with a new one (see page ).

HINT:

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

3.	CHECK FOR DTC

(a) Clear the DTC (see page ).

(b) Check for DTC (see page ).

OK:

DTC is not output.

END (AIR MIX SERVO MOTOR IS DEFECTIVE)

4.	REPLACE AIR CONDITIONING HARNESS

(a) Replace the air conditioning harness.

5.	CHECK FOR DTC

(a) Clear the DTC (see page ).

(b) Check for DTC again (see page ).

OK:

DTC is not output.

END (AIR CONDITIONING HARNESS IS DEFECTIVE)

REPLACE AIR CONDITIONING AMPLIFIER

Passenger Side Cool Air Bypass Damper Control (B1445/45)

BUS IC Communication Malfunction (B1497/97)

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