Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Front Left Seat Heat Sensor Circuit (B14C1)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Interior / Seat / Seat Heater System / Front Left Seat Heat Sensor Circuit (B14C1)

DESCRIPTION

Output to the front seat cushion heater temperature sensor stops if one of the following occurs: 1) the temperature sensor is open or shorted; or 2) the temperature sensor is damaged and its output value does not change.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B14C1

Front Left Seat Heat Sensor Circuit

Seat heater temperature sensor malfunction
  • Air conditioning amplifier assembly
  • Front Seat Cushion Heater LH (Seat Heater Assembly)*1
  • Front Seat Cushion Heater (Front Seat Cushion Pad with Cover LH)*2
  • Wire harness or connector
  • *1: for Standard Seat Type
  • *2: for Sports Seat Type

WIRING DIAGRAM

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 B14C1 is not output.

Result

Proceed to

OK

A

NG (for Standard Seat Type)

B

NG (for Sports Seat Type)

C
A

USE SIMULATION METHOD TO CHECK

C

GO TO STEP 5

B

3.

INSPECT FRONT SEAT CUSHION HEATER LH (SEAT HEATER ASSEMBLY)

(a) Remove the front seat cushion heater LH (seat heater assembly).

Click here

(b) Inspect the front seat cushion heater LH (seat heater assembly).

Click here

NG

REPLACE FRONT SEAT CUSHION HEATER LH (SEAT HEATER ASSEMBLY)

OK

4.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - FRONT SEAT CUSHION HEATER LH (SEAT HEATER ASSEMBLY))

(a) Disconnect the J42 and J48 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

J48-17 (TSL) - c8-6 (THR)

Always

Below 1 Ω

J48-17 (TSL) or c8-6 (THR) - Body ground

Always

10 kΩ or higher

J42-8 (SG-5) - c8-4 (PR)

Always

Below 1 Ω

J42-8 (SG-5) or c8-4 (PR) - Body ground

Always

10 kΩ or higher
OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

5.

INSPECT FRONT SEAT CUSHION HEATER (FRONT SEAT CUSHION PAD WITH COVER LH)

(a) Remove the front seat cushion heater (front seat cushion pad with cover LH).

Click here

(b) Inspect the front seat cushion heater (front seat cushion pad with cover LH).

Click here

NG

REPLACE FRONT SEAT CUSHION HEATER (FRONT SEAT CUSHION PAD WITH COVER LH)

OK

6.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - FRONT SEAT CUSHION HEATER (FRONT SEAT CUSHION PAD WITH COVER LH))

(a) Disconnect the J42 and J48 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

J48-17 (TSL) - c8-6 (THR)

Always

Below 1 Ω

J48-17 (TSL) or c8-6 (THR) - Body ground

Always

10 kΩ or higher

J42-8 (SG-5) - c8-4 (PR)

Always

Below 1 Ω

J42-8 (SG-5) or c8-4 (PR) - Body ground

Always

10 kΩ or higher
OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
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