Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual: Park / Neutral Position Switch Circuit

Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual / Vehicle Interior / Seat / Rear Power Seat Control System(for Second Row) / Park / Neutral Position Switch Circuit

DESCRIPTION

The fold seat control ECU receives switch operation signals, the back door courtesy light switch assembly signal*1, rear door courtesy light switch assembly signal*2 and driving condition signal and operates the rear power seat according these signals.

  • *1: When using fold seat switch assembly
  • *2: When using rear power seat switch

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Before replacing the main body ECU (multiplex network body ECU), refer to Registration.

PROCEDURE

1.

CHECK FOLD SEAT CONTROL ECU (PARK/NEUTRAL POSITION SWITCH SIGNAL)

*A

for Rear RH Seat

*B

for Rear LH Seat

*a

Component with harness connected

(Fold Seat Control ECU)

(a) Remove the fold seat control ECU with its connectors still connected.

  • for Rear LH Seat: Click here
  • for Rear RH Seat: Click here

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

Standard Voltage:

for Rear RH Seat

Tester Connection

Condition

Specified Condition

x3-17 (P) - Body ground
  • Engine switch on (IG), shift lever in P or N → not in P and N
  • Engine switch on (IG), stop light switch assembly on → off
  • Engine switch on (IG), parking brake applied → released

11 to 14 V → Below 1 V

Engine switch off

11 to 14 V
for Rear LH Seat

Tester Connection

Condition

Specified Condition

y3-17 (P) - Body ground
  • Engine switch on (IG), shift lever in P or N → not in P and N
  • Engine switch on (IG), stop light switch assembly on → off
  • Engine switch on (IG), parking brake applied → released

11 to 14 V → Below 1 V

Engine switch off

11 to 14 V
OK

GO TO PROBLEM SYMPTOMS TABLE

NG

2.

CHECK HARNESS AND CONNECTOR (FOLD SEAT CONTROL ECU - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU))

(a) Disconnect the x3*1 or y3*2 fold seat control ECU connector.

  • *1: for Rear RH Seat
  • *2: for Rear LH Seat

(b) Disconnect the J9 main body ECU (multiplex network body ECU) connector.

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

Standard Resistance:

for Rear RH Seat

Tester Connection

Condition

Specified Condition

x3-17 (P) - J9-16 (SFTP)

Always

Below 1 Ω

x3-17 (P) or J9-16 (SFTP) - Body ground

Always

10 kΩ or higher

for Rear LH Seat

Tester Connection

Condition

Specified Condition

y3-17 (P) - J9-16 (SFTP)

Always

Below 1 Ω

y3-17 (P) or J9-16 (SFTP) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

CHECK FOLD SEAT CONTROL ECU

(a) Replace the fold seat control ECU with a new or known good one.

  • for Rear LH Seat: Click here
  • for Rear RH Seat: Click here

(b) Check the operation of the rear power seat.

Click here

OK:

The rear power seat operates normally.

OK

END (FOLD SEAT CONTROL ECU WAS DEFECTIVE)
NG

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

    Problem Symptoms Table
    PROBLEM SYMPTOMS TABLE HINT: Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of ...

    Rear Door Courtesy Switch Circuit
    DESCRIPTION HINT: The rear door courtesy light switch is a collective term for the rear door courtesy light switch (for RH) and the rear door courtesy light switch (for LH). The fold seat control ECU ...

    Other materials:

    Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual > Lighting System (w/o Automatic Headlight Beam Level Control System): Problem Symptoms Table
    PROBLEM SYMPTOMS TABLE NOTICE: Before replacing the main body ECU (multiplex network body ECU), refer to Registration. Click here When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, t ...

    Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual > Occupant Classification System: Occupant Classification ECU Malfunction (B1795)
    DESCRIPTION DTC B1795 is stored when a malfunction is detected in the occupant detection ECU. DTC No. Detection Item DTC Detection Condition Trouble Area B1795 Occupant Classification ECU Malfunction Occupant detection ECU malfunction Occupant detection ECU CAUTION / NOTICE / H ...

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual

    © 2026 Copyright www.lexusrx.net
    0.0089