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

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Interior / Lighting (int) / Lighting System / Door Courtesy Switch Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) detects the condition of the front door courtesy light switch assembly.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Before replacing the main body ECU (multiplex network body ECU), refer to Registration.

Click here

PROCEDURE

1.

READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Main Body / Data List.

(e) Read the Data List according to the display on the Techstream.

Body Electrical > Main Body > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

RR Door Courtesy SW

Rear door courtesy light switch assembly RH signal

ON or OFF

ON: Rear door RH open

OFF: Rear door RH closed

-

RL Door Courtesy SW

Rear door courtesy light switch assembly LH signal

ON or OFF

ON: Rear door LH open

OFF: Rear door LH closed

-

FR Door Courtesy SW

Front door courtesy light switch assembly RH signal

ON or OFF

ON: Front door RH open

OFF: Front door RH closed

-

FL Door Courtesy SW

Front door courtesy light switch assembly LH signal

ON or OFF

ON: Front door LH open

OFF: Front door LH closed

-
Body Electrical > Main Body > Data List

Tester Display

RR Door Courtesy SW

RL Door Courtesy SW

FR Door Courtesy SW

FL Door Courtesy SW

OK:

Normal conditions listed above are displayed.

Result

Proceed to

OK

A

FR Door Courtesy SW is not normal

B

FL Door Courtesy SW is not normal

C

RR Door Courtesy SW is not normal

D

RL Door Courtesy SW is not normal

E
A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

C

GO TO STEP 4

D

GO TO STEP 6

E

GO TO STEP 9

B

2.

INSPECT FRONT DOOR COURTESY LIGHT SWITCH ASSEMBLY RH

(a) Remove the front door courtesy light switch assembly RH.

Click here

(b) Inspect the front door courtesy light switch assembly RH.

Click here

OK:

Front door courtesy light switch assembly RH is normal.

NG

REPLACE FRONT DOOR COURTESY LIGHT SWITCH ASSEMBLY RH

OK

3.

CHECK HARNESS AND CONNECTOR (FRONT DOOR COURTESY LIGHT SWITCH ASSEMBLY RH - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU))

(a) Disconnect the J8 main body ECU (multiplex network body ECU) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

R4-1 - J8-27 (FRCY)

Always

Below 1 Ω

R4-1 or J8-27 (FRCY) - Body ground

Always

10 kΩ or higher
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.

INSPECT FRONT DOOR COURTESY LIGHT SWITCH ASSEMBLY LH

(a) Remove the front door courtesy light switch assembly LH.

Click here

(b) Inspect the front door courtesy light switch assembly LH.

Click here

OK:

Front door courtesy light switch assembly LH is normal.

NG

REPLACE FRONT DOOR COURTESY LIGHT SWITCH ASSEMBLY LH

OK

5.

CHECK HARNESS AND CONNECTOR (FRONT DOOR COURTESY LIGHT SWITCH ASSEMBLY LH - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU))

(a) Disconnect the J8 main body ECU (multiplex network body ECU) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

S3-1 - J8-6 (FLCY)

Always

Below 1 Ω

S3-1 or J8-6 (FLCY) - Body ground

Always

10 kΩ or higher
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.

INSPECT REAR DOOR COURTESY LIGHT SWITCH ASSEMBLY RH

(a) Remove the rear door courtesy light switch assembly RH.

Click here

(b) Inspect the rear door courtesy light switch assembly RH.

Click here

NG

REPLACE REAR DOOR COURTESY LIGHT SWITCH ASSEMBLY RH

OK

7.

CHECK HARNESS AND CONNECTOR (REAR DOOR COURTESY LIGHT SWITCH ASSEMBLY RH - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

(a) Disconnect the 2A instrument panel junction block assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

R16-1 - 2A-31

Always

Below 1 Ω

R16-1 or 2A-31 - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

8.

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

(a) Remove the instrument panel junction block assembly.

Click here

(b) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

Click here

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

*a

Component without harness connected

(Instrument Panel Junction Block Assembly)

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

2A-31 - MB-2 (RCTY)

Always

Below 1 Ω
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

9.

INSPECT REAR DOOR COURTESY LIGHT SWITCH ASSEMBLY LH

(a) Remove the rear door courtesy light switch assembly LH.

Click here

(b) Inspect the rear door courtesy light switch assembly LH.

Click here

NG

REPLACE REAR DOOR COURTESY LIGHT SWITCH ASSEMBLY LH

OK

10.

CHECK HARNESS AND CONNECTOR (REAR DOOR COURTESY LIGHT SWITCH ASSEMBLY LH - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

S16-1 - 2D-24

Always

Below 1 Ω

S16-1 or 2D-24 - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

11.

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

(a) Remove the instrument panel junction block assembly.

Click here

(b) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

Click here

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

*a

Component without harness connected

(Instrument Panel Junction Block Assembly)

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

2D-24 - MB-13 (LCTY)

Always

Below 1 Ω
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

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