Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual: Air Outlet Damper Control Servo Motor Circuit(Driver Side Front A/C Rear Air Flow) (B1486/86)

DESCRIPTION

The Rear No. 1 cooling unit 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 or reverse) based on these signals to move the Rear No. 1 cooling unit damper servo sub-assembly to the appropriate position, which controls the air outlet switching.

The air conditioning amplifier assembly communicates with the servo through a communication/driver IC and wiring assembly called the No. 2 air conditioning harness assembly.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Memory
B1486/86	Air Outlet Damper Control Servo Motor Circuit(Driver Side Front A/C Rear Air Flow)	Rear air outlet damper position sensor value does not change even if air conditioning amplifier assembly operates Rear No. 1 cooling unit damper servo sub-assembly	Rear No. 1 cooling unit damper servo sub-assembly No. 2 air conditioning harness assembly Air conditioning amplifier assembly Harness or connector	Memorized (30 sec. or more)*

WIRING DIAGRAM

CAUTION / NOTICE / HINT

HINT:

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

PROCEDURE

1.	READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Operate the rear passenger side mode 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 Outlet Servo Pls (F&R D)	Rear No. 1 cooling unit damper servo sub-assembly target pulse	Min.: 128 Max.: 383	FACE: 276 (pulse) B/L: 233 (pulse) FOOT: 200 (pulse)	-
A/O Servo Actual Pulse(F&R D)	Rear No. 1 cooling unit damper servo sub-assembly actual pulse	Min.: 128 Max.: 383	FACE: 276 (pulse) B/L: 233 (pulse) FOOT: 200 (pulse)	-

Body Electrical > Air Conditioner > Data List

Tester Display
Air Outlet Servo Pls (F&R D)
A/O Servo Actual Pulse(F&R D)

OK:

When the rear passenger side mode switch is operated, the actual pulse changes following the target pulse.

Result	Proceed to
Target pulse changes but actual pulse does not change	A
Target pulse and actual pulse do 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

B

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

C

GO TO STEP 5

D

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

A

2.	CHECK HARNESS AND CONNECTOR (NO. 2 AIR CONDITIONING HARNESS ASSEMBLY - AIR CONDITIONING AMPLIFIER ASSEMBLY)

(a) Disconnect the R52 No. 2 air conditioning harness assembly connector.

(b) Disconnect the J48 air conditioning amplifier assembly connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
R52-4 (RBBU) - J48-3 (RBBU)	Always	Below 1 Ω
R52-3 (RBUS) - J48-22 (RBUS)	Always	Below 1 Ω
R52-2 (RBUG) - J48-2 (RBUG)	Always	Below 1 Ω
R52-4 (RBBU) or J48-3 (RBBU) - Other terminals and body ground	Always	10 kΩ or higher
R52-3 (RBUS) or J48-22 (RBUS) - Other terminals and body ground	Always	10 kΩ or higher
R52-2 (RBUG) or J48-2 (RBUG) - Other terminals and body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.	CHECK REAR NO. 1 COOLING UNIT DAMPER SERVO SUB-ASSEMBLY

(a) Replace the Rear No. 1 cooling unit 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) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Air Conditioner / Trouble Codes.

(f) Clear the DTC.

Body Electrical > Air Conditioner > Clear DTCs

(g) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

OK:

DTC B1486/86 is not output.

NG

END (REAR NO. 1 COOLING UNIT DAMPER SERVO SUB-ASSEMBLY WAS DEFECTIVE)

OK

4.	CHECK NO. 2 AIR CONDITIONING HARNESS ASSEMBLY

(a) Replace the No. 2 air conditioning harness assembly.

Click here

HINT:

Since the No. 2 air conditioning harness assembly cannot be inspected while it is removed from the vehicle, replace the No. 2 air conditioning harness assembly with a new or known good one and check that the condition returns to normal.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Air Conditioner / Trouble Codes.

(f) Clear the DTC.

Body Electrical > Air Conditioner > Clear DTCs

(g) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

OK:

DTC B1486/86 is not output.

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

END (NO. 2 AIR CONDITIONING HARNESS ASSEMBLY WAS DEFECTIVE)

5.	RECONFIRM DTC OUTPUT

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Air Conditioner / Trouble Codes.

(e) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result	Proceed to
DTC B1486/86 is output	A
DTC B1486/86 is not output	B

A

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

B

USE SIMULATION METHOD TO CHECK