Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: IG Signal Circuit

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

DESCRIPTION

Based on the engine switch signal, each fold seat control ECU determines the driving condition of the vehicle and enables or disables the fold and return functions.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • When the 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

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

A

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

B

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

C
B

GO TO STEP 4

C

GO TO STEP 6

A

2.

CHECK HARNESS AND CONNECTOR (IG POWER SOURCE)

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

*A

for RH seat

*B

for LH seat

*a

Front view of wire harness connector

(Fold Seat Control ECU (RH/LH Seat))

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

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

x15-3 (IG) - Body ground

Engine switch off

Below 1 V

Engine switch on (IG)

11 to 14 V

y15-3 (IG) - Body ground

Engine switch off

Below 1 V

Engine switch on (IG)

11 to 14 V
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

3.

CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - FOLD SEAT CONTROL ECU (RH/LH SEAT))

(a) Disconnect the 2B and 2D instrument panel junction block assembly connectors.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2B-30 or x15-3 (IG) - Body ground

Always

10 kΩ or higher

2D-35 or y15-3 (IG) - Body ground

Always

10 kΩ or higher
OK

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

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

*a

Component with harness connected

(Instrument Panel Junction Block Assembly)

-

-

Standard Voltage:

Tester Connection

Condition

Specified Condition

2B-30 - Body ground

Engine switch off

Below 1 V

Engine switch on (IG)

11 to 14 V
NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

OK

5.

CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - FOLD SEAT CONTROL ECU (RH SEAT))

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

(b) Disconnect the 2B instrument panel junction block assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2B-30 - x15-3 (IG)

Always

Below 1 Ω
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

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

*a

Component with harness connected

(Instrument Panel Junction Block Assembly)

-

-

Standard Voltage:

Tester Connection

Condition

Specified Condition

2D-35 - Body ground

Engine switch off

Below 1 V

Engine switch on (IG)

11 to 14 V
NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

OK

7.

CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - FOLD SEAT CONTROL ECU (LH SEAT))

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

(b) Disconnect the 2D instrument panel junction block assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2D-35 - y15-3 (IG)

Always

Below 1 Ω
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
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    TERMINALS OF ECU CHECK FOLD SEAT CONTROL ECU (RH SEAT) (a) Disconnect the x15 and x16 fold seat control ECU (RH seat) connectors. (b) Measure the resistance and voltage according to the value(s) in t ...

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    DESCRIPTION Each fold seat control ECU receives the driving condition signal and engine switch signal from the main body ECU (multiplex network body ECU) to determine the driving state of the vehicle ...

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