Lexus NX: Air Inlet Damper Control Servo Motor Circuit (B1442)

DESCRIPTION

The No. 1 blower damper servo sub-assembly sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal, reverse) based on the signals to move the air inlet mode selection No. 1 blower damper servo sub-assembly to any position, which controls the intake air settings (FRESH, FRESH/RECIRCULATION, and RECIRCULATION).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Memory	Note
B1442	Air Inlet Damper Control Servo Motor Circuit	Air inlet damper position sensor value does not change even if air conditioning amplifier assembly operates No. 1 blower damper servo sub-assembly	No. 1 blower damper servo sub-assembly No. 1 air conditioning radiator damper servo sub-assembly Air conditioning harness assembly Air conditioning amplifier assembly	Memorized (30 seconds or more)	-

HINT:

The air conditioning amplifier assembly stores the DTC of the respective malfunction if it has occurred for the period of time indicated in the brackets.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

HINT:

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

PROCEDURE

1.	CHECK FOR DTC

(a) Clear the DTC.

Click here

Body Electrical > Air Conditioner > Clear DTCs

(b) Check for DTC.

Click here

Body Electrical > Air Conditioner > Trouble Codes

Result	Proceed to
DTC B1442 is not output	A
DTC B1442 is output	B
DTC B1442 and B1497 are output	C

A

USE SIMULATION METHOD TO CHECK

C

GO TO DTC B1497

B

2.	READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Operate the recirculation/fresh switch.

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

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

Body Electrical > Air Conditioner > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Air Inlet Damper Targ Pulse	No. 1 blower damper servo sub-assembly target pulse	Min.: 128 Max.: 383	RECIRCULATION: 258 (pulse) FRESH: 235 (pulse)	-
Air Inlet Damper Actual Pulse	No. 1 blower damper servo sub-assembly actual pulse	Min.: 128 Max.: 383	RECIRCULATION: 258 (pulse) FRESH: 235 (pulse)	-

Body Electrical > Air Conditioner > Data List

Tester Display
Air Inlet Damper Targ Pulse
Air Inlet Damper Actual Pulse

OK:

When the recirculation/fresh switch is turned to recirculation mode or fresh mode, the actual pulse changes following the target pulse.

Result	Proceed to
Target pulse and actual pulse do not change	A
Target pulse changes but actual pulse does not change	B
Actual pulse changes following the target pulse (When troubleshooting according to the DTC)	C
Actual pulse changes following the target pulse (When troubleshooting according to Problem Symptoms Table)	D

A

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

C

GO TO STEP 6

D

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

B

3.	CHECK NO. 1 BLOWER DAMPER SERVO SUB-ASSEMBLY

(a) Replace the No. 1 blower damper servo sub-assembly.

Click here

HINT:

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

(b) Clear the DTC.

Click here

Body Electrical > Air Conditioner > Clear DTCs

(c) Check for DTC.

Click here

Body Electrical > Air Conditioner > Trouble Codes

Result	Proceed to
DTC B1442 is not output	A
DTC B1442 is output	B

A

END (NO. 1 BLOWER DAMPER SERVO SUB-ASSEMBLY IS DEFECTIVE)

B

4.	CHECK NO. 1 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY

(a) Replace the No. 1 air conditioning radiator damper servo sub-assembly.

Click here

HINT:

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

(b) Clear the DTC.

Click here

Body Electrical > Air Conditioner > Clear DTCs

(c) Check for DTC.

Click here

Body Electrical > Air Conditioner > Trouble Codes

Result	Proceed to
DTC B1442 is not output	A
DTC B1442 is output	B

A

END (NO. 1 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY IS DEFECTIVE)

B

5.	CHECK AIR CONDITIONING HARNESS ASSEMBLY

(a) Replace the air conditioning harness assembly.

Click here

HINT:

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

(b) Clear the DTC.

Click here

Body Electrical > Air Conditioner > Clear DTCs

(c) Check for DTC.

Click here

Body Electrical > Air Conditioner > Trouble Codes

Result	Proceed to
DTC B1442 is not output	A
DTC B1442 is output	B

A

END (AIR CONDITIONING HARNESS ASSEMBLY IS DEFECTIVE)

B

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

6.	CHECK FOR DTC

(a) Clear the DTC.

Click here

Body Electrical > Air Conditioner > Clear DTCs

(b) Check for DTC.

Click here

Body Electrical > Air Conditioner > Trouble Codes

Result	Proceed to
DTC B1442 is not output	A
DTC B1442 is output	B

A

USE SIMULATION METHOD TO CHECK

B

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

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