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 Third Row) / Fold Seat Switch Circuit

DESCRIPTION

When a switch of the fold seat switch assembly or No. 1 fold seat switch assembly is pushed, the fold seat control ECU receives a switch operation signal and operates the fold or return function.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When a fold seat control ECU (RH/LH seat) is replaced, it is necessary to perform initialization.

Click here

PROCEDURE

1.

CHECK REAR POWER SEAT CONTROL SYSTEM (for Third Row)

(a) Check that the rear power seat control system (for Third Row) function operates normally.

Result

Proceed to

When fold seat switch assembly operated

Fold/Return functions of both rear No.2 power seats do not operate normally.

A

Fold function of rear No. 2 power seat RH does not operate normally.

B

Return function of rear No. 2 power seat RH does not operate normally.

C

Fold function of rear No. 2 power seat LH does not operate normally.

D

Return function of rear No. 2 power seat LH does not operate normally.

E

When No. 1 fold seat switch assembly operated

Fold/Return functions of both rear No.2 power seats do not operate normally.

F

Fold function of rear No. 2 power seat RH does not operate normally.

G

Return function of rear No. 2 power seat RH does not operate normally.

H

Fold function of rear No. 2 power seat LH does not operate normally.

I

Return function of rear No. 2 power seat LH does not operate normally.

J
B

GO TO STEP 4

C

GO TO STEP 7

D

GO TO STEP 10

E

GO TO STEP 13

F

GO TO STEP 16

G

GO TO STEP 18

H

GO TO STEP 21

I

GO TO STEP 24

J

GO TO STEP 27

A

2.

INSPECT FOLD SEAT SWITCH ASSEMBLY (GROUND)

(a) Remove the fold seat switch assembly.

Click here

(b) Inspect the fold seat switch assembly. (Ground)

Click here

NG

REPLACE FOLD SEAT SWITCH ASSEMBLY

OK

3.

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

R54-7 (E) - Body ground

Always

Below 1 Ω
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.

INSPECT FOLD SEAT SWITCH ASSEMBLY (FOLD SWITCH (RH))

(a) Remove the fold seat switch assembly.

Click here

(b) Inspect the fold seat switch assembly. (Fold Switch (RH))

Click here

NG

REPLACE FOLD SEAT SWITCH ASSEMBLY

OK

5.

CHECK FOLD SEAT CONTROL ECU (RH SEAT)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

R54-8 (FLDR) - Body ground

Always

11 to 14 V
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

6.

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

(a) Disconnect the x15 fold seat control ECU (RH seat) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

x15-26 (RCLF) - R54-8 (FLDR)

Always

Below 1 Ω

x15-26 (RCLF) or R54-8 (FLDR) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (RH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.

INSPECT FOLD SEAT SWITCH ASSEMBLY (RETURN SWITCH (RH))

(a) Remove the fold seat switch assembly.

Click here

(b) Inspect the fold seat switch assembly. (Return Switch (RH))

Click here

NG

REPLACE FOLD SEAT SWITCH ASSEMBLY

OK

8.

CHECK FOLD SEAT CONTROL ECU (RH SEAT)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

R54-3 (RTNR) - Body ground

Always

11 to 14 V
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

9.

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

(a) Disconnect the x15 fold seat control ECU (RH seat) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

x15-25 (RCLR) - R54-3 (RTNR)

Always

Below 1 Ω

x15-25 (RCLR) or R54-3 (RTNR) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (RH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

10.

INSPECT FOLD SEAT SWITCH ASSEMBLY (FOLD SWITCH (LH))

(a) Remove the fold seat switch assembly.

Click here

(b) Inspect the fold seat switch assembly. (Fold Switch (LH))

Click here

NG

REPLACE FOLD SEAT SWITCH ASSEMBLY

OK

11.

CHECK FOLD SEAT CONTROL ECU (LH SEAT)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

R54-6 (FLDL) - Body ground

Always

11 to 14 V
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

12.

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

(a) Disconnect the y15 fold seat control ECU (LH seat) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

y15-26 (RCLF) - R54-6 (FLDL)

Always

Below 1 Ω

y15-26 (RCLF) or R54-6 (FLDL) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (LH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

13.

INSPECT FOLD SEAT SWITCH ASSEMBLY (RETURN SWITCH (LH))

(a) Remove the fold seat switch assembly.

Click here

(b) Inspect the fold seat switch assembly. (Return Switch (LH))

Click here

NG

REPLACE FOLD SEAT SWITCH ASSEMBLY

OK

14.

CHECK FOLD SEAT CONTROL ECU (LH SEAT)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

R54-1 (RTNL) - Body ground

Always

11 to 14 V
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

15.

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

(a) Disconnect the y15 fold seat control ECU (LH seat) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

y15-25 (RCLR) - R54-1 (RTNL)

Always

Below 1 Ω

y15-25 (RCLR) or R54-1 (RTNL) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (LH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

16.

INSPECT NO. 1 FOLD SEAT SWITCH ASSEMBLY (GROUND)

(a) Remove the No. 1 fold seat switch assembly.

Click here

(b) Inspect the No. 1 fold seat switch assembly. (Ground)

Click here

NG

REPLACE NO. 1 FOLD SEAT SWITCH ASSEMBLY

OK

17.

CHECK HARNESS AND CONNECTOR (NO. 1 FOLD SEAT SWITCH ASSEMBLY - BODY GROUND)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

S88-7 (E) - Body ground

Always

Below 1 Ω
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

18.

INSPECT NO. 1 FOLD SEAT SWITCH ASSEMBLY (FOLD SWITCH (RH))

(a) Remove the No. 1 fold seat switch assembly.

Click here

(b) Inspect the No. 1 fold seat switch assembly. (Fold Switch (RH))

Click here

NG

REPLACE NO. 1 FOLD SEAT SWITCH ASSEMBLY

OK

19.

CHECK FOLD SEAT CONTROL ECU (RH SEAT)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

S88-6 (FOLD) - Body ground

Always

11 to 14 V
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

20.

CHECK HARNESS AND CONNECTOR (FOLD SEAT CONTROL ECU (RH SEAT) - NO. 1 FOLD SEAT SWITCH ASSEMBLY)

(a) Disconnect the x15 fold seat control ECU (RH seat) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

x15-12 (FOLD) - S88-6 (FOLD)

Always

Below 1 Ω

x15-12 (FOLD) or S88-6 (FOLD) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (RH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

21.

INSPECT NO. 1 FOLD SEAT SWITCH ASSEMBLY (RETURN SWITCH (RH))

(a) Remove the No. 1 fold seat switch assembly.

Click here

(b) Inspect the No. 1 fold seat switch assembly. (Return Switch (RH))

Click here

NG

REPLACE NO. 1 FOLD SEAT SWITCH ASSEMBLY

OK

22.

CHECK FOLD SEAT CONTROL ECU (RH SEAT)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

S88-1 (RTRN) - Body ground

Always

11 to 14 V
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

23.

CHECK HARNESS AND CONNECTOR (FOLD SEAT CONTROL ECU (RH SEAT) - NO. 1 FOLD SEAT SWITCH ASSEMBLY)

(a) Disconnect the x15 fold seat control ECU (RH seat) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

x15-7 (RTRN) - S88-1 (RTRN)

Always

Below 1 Ω

x15-7 (RTRN) or S88-1 (RTRN) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (RH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

24.

INSPECT NO. 1 FOLD SEAT SWITCH ASSEMBLY (FOLD SWITCH (LH))

(a) Remove the No. 1 fold seat switch assembly.

Click here

(b) Inspect the No. 1 fold seat switch assembly. (Fold Switch (LH))

Click here

NG

REPLACE NO. 1 FOLD SEAT SWITCH ASSEMBLY

OK

25.

CHECK FOLD SEAT CONTROL ECU (LH SEAT)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

S88-8 (FOLD) - Body ground

Engine switch off

11 to 14 V
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

26.

CHECK HARNESS AND CONNECTOR (FOLD SEAT CONTROL ECU (LH SEAT) - NO. 1 FOLD SEAT SWITCH ASSEMBLY)

(a) Disconnect the y15 fold seat control ECU (LH seat) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

y15-12 (FOLD) - S88-8 (FOLD)

Always

Below 1 Ω

y15-12 (FOLD) or S88-8 (FOLD) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (LH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

27.

INSPECT NO. 1 FOLD SEAT SWITCH ASSEMBLY (RETURN SWITCH (LH))

(a) Remove the No. 1 fold seat switch assembly.

Click here

(b) Inspect the No. 1 fold seat switch assembly. (Return Switch (LH))

Click here

NG

REPLACE NO. 1 FOLD SEAT SWITCH ASSEMBLY

OK

28.

CHECK FOLD SEAT CONTROL ECU (LH SEAT)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

S88-3 (RTRN) - Body ground

Always

11 to 14 V
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

29.

CHECK HARNESS AND CONNECTOR (FOLD SEAT CONTROL ECU (LH SEAT) - NO. 1 FOLD SEAT SWITCH ASSEMBLY)

(a) Disconnect the y15 fold seat control ECU (LH seat) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

y15-7 (RTRN) - S88-3 (RTRN)

Always

Below 1 Ω

y15-7 (RTRN) or S88-3 (RTRN) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (LH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
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