Lexus NX: Rear Left Seat Heat Sensor Circuit (B14C3)

Lexus NX Service Manual / Vehicle Interior / Seat / Seat Heater System / Rear Left Seat Heat Sensor Circuit (B14C3)

DESCRIPTION

Power supply to the temperature sensor built into the rear seat cushion heater stops if one of the following occurs: 1) an open or short occurs in the temperature sensor circuit; or 2) the temperature sensor is damaged and its output value does not change.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B14C3

Rear Left Seat Heat Sensor Circuit

Seat heater temperature sensor malfunction

  • Air conditioning amplifier assembly
  • Bench type rear seat cushion cover
  • Harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • If the auxiliary battery voltage is low, the seat heater system may not operate. When "High Power Consumption / Partial Limit On AC/Heater Operation" is displayed on the multi-information display in the combination meter assembly, inspect the auxiliary battery, referring to On-vehicle Inspection for the charging system.

    HINT:

    If the auxiliary battery voltage is low, "Operation Limitation Control History Count (Level 1)" and "Operation Limitation Control History Count (Level 2) is counted.

    Click here

    Click here

  • If the auxiliary battery voltage is low, the seat heater system may not operate. Refer to Data List for the power steering system.
    • for Manual Tilt and Manual Telescopic Steering Column:
    • for Power Tilt and Power Telescopic Steering Column:
  • When the auxiliary battery is disconnected or the air conditioning amplifier assembly is replaced, be sure to perform servo motor initialization.

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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 B14C3 is not output.

OK

USE SIMULATION METHOD TO CHECK

NG

3.

READ VALUE USING TECHSTREAM (RL SEAT HEATER TEMPERATURE)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

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

(e) Read the Data List according to the display on the Techstream.

Body Electrical > Air Conditioner > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

RL Seat Heater Temperature

Rear seat LH heater temperature

-29.7°C to 59.55°C

  • HI: 41 to 42 °C (106 to 108 °F)
  • MID: 37 to 38 °C (99 to 100 °F)
  • LO: 35 to 36 °C (95 to 97 °F)

Refreshing seat switch (for Rear seat LH) is on (w/ Rear Seat Heater)

Body Electrical > Air Conditioner > Data List

Tester Display

RL Seat Heater Temperature

OK:

On the Techstream screen, the seat heater temperature is as specified in the normal condition column.

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

4.

INSPECT BENCH TYPE REAR SEAT CUSHION COVER

(a) Remove the bench type rear seat cushion cover.

  • for Manual Seat:
  • for Power Seat:

(b) Inspect the bench type rear seat cushion cover.

  • for Manual Seat:
  • for Power Seat:
NG

REPLACE BENCH TYPE REAR SEAT CUSHION COVER

OK

5.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - BENCH TYPE REAR SEAT CUSHION COVER)

(a) Disconnect the I54 air conditioning amplifier assembly connector.

(b) Disconnect the h6 bench type rear seat cushion cover connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

I54-20 (TFAL) - i6-3

Always

Below 1 Ω

I54-20 (TFAL) or i6-3 - Body ground

Always

10 kΩ or higher

I54-23 (SG-7) - i6-2

Always

Below 1 Ω

I54-23 (SG-7) or i6-2 - Body ground

Always

10 kΩ or higher

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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