Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Position Sensor Circuit

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

DESCRIPTION

When a fold seat control ECU receives signals from the fold seat switch assembly or No. 1 fold seat switch assembly, it operates the reclining motor and lifter motor of its corresponding rear No. 2 power seat. When the reclining motor or lifter motor is operating, the position sensor (Hall IC) in it outputs signals. These signals are received by the corresponding fold seat control ECU, which uses them to detect the position of the seatback and seat cushion.

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

  • When No. 2 seat cushion frame sub-assembly RH, No. 2 seat cushion frame sub-assembly LH, No. 2 seatback frame sub-assembly RH or No. 2 seatback frame sub-assembly LH is removed and reinstalled, 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

Fold/Return functions of rear No. 2 power seat RH do not operate normally.

A

Fold/Return functions of rear No. 2 power seat LH do not operate normally.

B
B

GO TO STEP 8

A

2.

CHECK FOLD SEAT CONTROL ECU (RH SEAT) (SENSOR POWER SOURCE)

(a) Disconnect the x13 No. 2 seat cushion frame sub-assembly RH connector.

(b) Disconnect the x14 No. 2 seatback frame sub-assembly RH connector.

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

Standard Voltage:

Lifter Motor

Tester Connection

Condition

Specified Condition

x13-5 - x13-6

Fold switch (RH) of fold seat switch assembly or No. 1 fold seat switch assembly pushed

5.5 to 10 V
Reclining Motor

Tester Connection

Condition

Specified Condition

x14-5 - x14-6

Return switch (RH) of fold seat switch assembly or No. 1 fold seat switch assembly pushed

5.5 to 10 V
NG

GO TO STEP 5

OK

3.

CHECK NO. 2 SEAT CUSHION FRAME SUB-ASSEMBLY RH (SENSOR SIGNAL)

(a) Reconnect the x13 No. 2 seat cushion frame sub-assembly RH connector.

*a

Component with harness connected

(No. 2 Seat Cushion Frame Sub-assembly RH (Lifter Motor))

(b) Using an oscilloscope, check the waveform.

OK:

Tester Connection

Condition

Specified Condition

x13-2 - Body ground

Lifter motor operating

Pulse generation

(Hi: 5.5 to 10 V, Lo: Below 1 V)
NG

GO TO STEP 6

OK

4.

CHECK NO. 2 SEATBACK FRAME SUB-ASSEMBLY RH (SENSOR SIGNAL)

(a) Reconnect the x14 No. 2 seatback frame sub-assembly RH connector.

*a

Component with harness connected

(No. 2 Seatback Frame Sub-assembly RH (Reclining Motor))

(b) Using an oscilloscope, check the waveform.

OK:

Tester Connection

Condition

Specified Condition

x14-2 - Body ground

Reclining motor operation

Pulse generation

(Hi: 5.5 to 10 V, Lo: Below 1 V)
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

GO TO STEP 7

5.

CHECK HARNESS AND CONNECTOR (NO. 2 SEAT CUSHION FRAME SUB-ASSEMBLY RH AND NO. 2 SEATBACK FRAME SUB-ASSEMBLY RH - FOLD SEAT CONTROL ECU (RH SEAT))

(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:

Lifter Motor

Tester Connection

Condition

Specified Condition

x13-5 - x15-11 (SV1)

Always

Below 1 Ω

x13-5 or x15-11 (SV1) - Body ground

Always

10 kΩ or higher

x13-6 - x15-8 (SG1)

Always

Below 1 Ω

x13-6 or x15-8 (SG1) - Body ground

Always

10 kΩ or higher
Reclining Motor

Tester Connection

Condition

Specified Condition

x14-5 - x15-31 (SV2)

Always

Below 1 Ω

x14-5 or x15-31 (SV2) - Body ground

Always

10 kΩ or higher

x14-6 - x15-28 (SG2)

Always

Below 1 Ω

x14-6 or x15-28 (SG2) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (RH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.

CHECK HARNESS AND CONNECTOR (NO. 2 SEAT CUSHION FRAME SUB-ASSEMBLY RH - FOLD SEAT CONTROL ECU (RH SEAT))

(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

x13-2 - x15-10 (SFLD)

Always

Below 1 Ω

x13-2 or x15-10 (SFLD) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (RH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.

CHECK HARNESS AND CONNECTOR (NO. 2 SEATBACK FRAME SUB-ASSEMBLY RH - FOLD SEAT CONTROL ECU (RH SEAT))

(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

x14-2 - x15-9 (SRCL)

Always

Below 1 Ω

x14-2 or x15-9 (SRCL) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (RH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

8.

CHECK FOLD SEAT CONTROL ECU (LH SEAT) (SENSOR POWER SOURCE)

(a) Disconnect the y13 No. 2 seat cushion frame sub-assembly LH connector.

(b) Disconnect the y14 No. 2 seatback frame sub-assembly LH connector.

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

Standard Voltage:

Lifter Motor

Tester Connection

Condition

Specified Condition

y13-5 - y13-6

Fold switch (LH) of fold seat switch assembly or No. 1 fold seat switch assembly pushed

5.5 to 10 V
Reclining Motor

Tester Connection

Condition

Specified Condition

y14-5 - y14-6

Return switch (LH) of fold seat switch assembly or No. 1 fold seat switch assembly pushed

5.5 to 10 V
NG

GO TO STEP 11

OK

9.

CHECK NO. 2 SEAT CUSHION FRAME SUB-ASSEMBLY LH (SENSOR SIGNAL)

(a) Reconnect the y13 No. 2 seat cushion frame sub-assembly LH connector.

*a

Component with harness connected

(No. 2 Seat Cushion Frame Sub-assembly LH (Lifter Motor))

(b) Using an oscilloscope, check the waveform.

OK:

Tester Connection

Condition

Specified Condition

y13-2 - Body ground

Lifter motor operation

Pulse generation

(Hi: 5.5 to 10 V, Lo: Below 1 V)
NG

GO TO STEP 12

OK

10.

CHECK NO. 2 SEATBACK FRAME SUB-ASSEMBLY LH (SENSOR SIGNAL)

(a) Reconnect the y14 No. 2 seatback frame sub-assembly LH connector.

*a

Component with harness connected

(No. 2 Seatback Frame Sub-assembly LH (Reclining Motor))

(b) Using an oscilloscope, check the waveform.

OK:

Tester Connection

Condition

Specified Condition

y14-2 - Body ground

Reclining motor operation

Pulse generation

(Hi: 5.5 to 10 V, Lo: Below 1 V)
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

GO TO STEP 13

11.

CHECK HARNESS AND CONNECTOR (NO. 2 SEAT CUSHION FRAME SUB-ASSEMBLY LH AND NO. 2 SEATBACK FRAME SUB-ASSEMBLY LH - FOLD SEAT CONTROL ECU (LH SEAT))

(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:

Lifter Motor

Tester Connection

Condition

Specified Condition

y13-5 - y15-11 (SV1)

Always

Below 1 Ω

y13-5 or y15-11 (SV1) - Body ground

Always

10 kΩ or higher

y13-6 - y15-8 (SG1)

Always

Below 1 Ω

y13-6 or y15-8 (SG1) - Body ground

Always

10 kΩ or higher
Reclining Motor

Tester Connection

Condition

Specified Condition

y14-5 - y15-31 (SV2)

Always

Below 1 Ω

y14-5 or y15-31 (SV2) - Body ground

Always

10 kΩ or higher

y14-6 - y15-28 (SG2)

Always

Below 1 Ω

y14-6 or y15-28 (SG2) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (LH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

12.

CHECK HARNESS AND CONNECTOR (NO. 2 SEAT CUSHION FRAME SUB-ASSEMBLY LH - FOLD SEAT CONTROL ECU (LH SEAT))

(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

y13-2 - y15-10 (SFLD)

Always

Below 1 Ω

y13-2 or y15-10 (SFLD) - Body ground

Always

10 kΩ or higher
OK

REPLACE FOLD SEAT CONTROL ECU (LH SEAT)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

13.

CHECK HARNESS AND CONNECTOR (NO. 2 SEATBACK FRAME SUB-ASSEMBLY LH - FOLD SEAT CONTROL ECU (LH SEAT))

(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

y14-2 - y15-9 (SRCL)

Always

Below 1 Ω

y14-2 or y15-9 (SRCL) - 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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