Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Lost Communication with Front Seat Temperature Adjustment Switch LIN (B14B5)

DESCRIPTION

The refreshing seat switch (for front side) communicates with the air conditioning amplifier assembly via LIN communication.

If the LIN communication system is malfunctioning, the air conditioning amplifier assembly will not operate even if the refreshing seat switch (for front side) is operated.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B14B5	Lost Communication with Front Seat Temperature Adjustment Switch LIN	Lost communication with the refreshing seat switch	Refreshing seat switch (for front side) Air conditioning amplifier assembly Wire harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Air Conditioner > Clear DTCs

NEXT

2.	CHECK FOR DTC

(a) Check for DTCs.

Click here

Body Electrical > Air Conditioner > Trouble Codes

OK:

DTC B14B5 is not output.

OK

USE SIMULATION METHOD TO CHECK

NG

3.	CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - REFRESHING SEAT SWITCH - BODY GROUND)

(a) Disconnect the J82 refreshing seat switch (for front side) switch connector.

*a Front view of wire harness connector (to Refreshing Seat Switch (for Front Side))

(b) Measure the voltage and resistance according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Condition	Specified Condition
J82-2 (IG) - Body ground	Engine switch on (IG)	11 to 14 V
J82-2 (IG) - Body ground	Engine switch off	Below 1 V

Standard Resistance:

Tester Connection	Condition	Specified Condition
J82-7 (E) - Body ground	Always	Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.	CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - REFRESHING SEAT SWITCH (FOR FRONT SIDE))

(a) Disconnect the J43 air conditioning amplifier assembly connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
J43-14 (LIN1) - J82-4 (LIN1)	Always	Below 1 Ω
J43-14 (LIN1) or J82-4 (LIN1) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.	REPLACE REFRESHING SEAT SWITCH (FOR FRONT SIDE)

(a) Temporarily replace the refreshing seat switch (for front side) with a new or known good one.

Click here

NEXT

6.

CLEAR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Air Conditioner > Clear DTCs

NEXT

7.	CHECK FOR DTC

(a) Check for DTCs.

Click here

Body Electrical > Air Conditioner > Trouble Codes

OK:

DTC B14B5 is not output.

OK

END (REFRESHING SEAT SWITCH WAS DEFECTIVE)

NG

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY