Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Fold Seat Switch Circuit

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Interior / Seat / Rear Power Seat Control System(for Second Row) / Fold Seat Switch Circuit

DESCRIPTION

When the fold seat switch assembly is operated, a switch operation signal is sent to the fold seat control ECU. According to the signal received, the fold seat control ECU operates the fold motor to perform a fold or return operation of the rear seatback.

WIRING DIAGRAM

PROCEDURE

1.

CHECK FOLD SEAT CONTROL ECU

(a) Check the fold seat control ECU.

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

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

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

Standard Voltage:

for Rear RH Seat

Tester Connection

Condition

Specified Condition

x3-26 (FOLD) - Body ground

Fold seat switch (for Rear Right Seat) off → on (fold)

11 to 14 V → Below 1 V

x3-25 (RTRN) - Body ground

Fold seat switch (for Rear Right Seat) off → on (return)

11 to 14 V → Below 1 V
for Rear LH Seat

Tester Connection

Condition

Specified Condition

y3-26 (FOLD) - Body ground

Fold seat switch (for Rear Left Seat) off → on (fold)

11 to 14 V → Below 1 V

y3-25 (RTRN) - Body ground

Fold seat switch (for Rear Left Seat) off → on (return)

11 to 14 V → Below 1 V

*A

for Rear RH Seat

*B

for Rear LH Seat

*a

Component with harness connected (Fold Seat Control ECU)
OK

GO TO PROBLEM SYMPTOMS TABLE

NG

2.

INSPECT FOLD SEAT SWITCH ASSEMBLY

(a) Remove the fold seat switch assembly.

Click here

(b) Inspect the fold seat switch assembly.

Click here

NG

REPLACE FOLD SEAT SWITCH ASSEMBLY

OK

3.

CHECK HARNESS AND CONNECTOR (FOLD SEAT SWITCH ASSEMBLY - FOLD SEAT CONTROL ECU AND BODY GROUND)

(a) Disconnect the R31 fold seat switch assembly connector.

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

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

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

Standard Resistance:

for Rear RH Seat

Tester Connection

Condition

Specified Condition

R31-6 (FOLD) - x3-26 (FOLD)

Always

Below 1 Ω

R31-6 (FOLD) or x3-26 (FOLD) - Body ground

Always

10 kΩ or higher

R31-1 (RTRN) - x3-25 (RTRN)

Always

Below 1 Ω

R31-1 (RTRN) or x3-25 (RTRN) - Body ground

Always

10 kΩ or higher

R31-7 (E) - Body ground

Always

Below 1 Ω
for Rear LH Seat

Tester Connection

Condition

Specified Condition

R31-8 (FOLD) - y3-26 (FOLD)

Always

Below 1 Ω

R31-8 (FOLD) or y3-26 (FOLD) - Body ground

Always

10 kΩ or higher

R31-3 (RTRN) - y3-25 (RTRN)

Always

Below 1 Ω

R31-3 (RTRN) or y3-25 (RTRN) - Body ground

Always

10 kΩ or higher

R31-7 (E) - Body ground

Always

Below 1 Ω
OK

REPLACE FOLD SEAT CONTROL ECU

NG

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