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)

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