Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Interior Light Auto Cut Circuit

DESCRIPTION

When the battery saving control operates, the main body ECU (multiplex network body ECU) controls the operation of the DOME CUT relay that is built into the instrument panel junction block assembly to turn off the interior lights.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.
  • Before replacing the main body ECU (multiplex network body ECU), refer to Registration.

    Click here

PROCEDURE

1.

PERFORM ACTIVE TEST 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 / Active Test.

(e) Perform the Active Test according to the display on the Techstream.

Body Electrical > Main Body > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Relay for Interior Light Auto Cut Function

DOME CUT relay

ON or OFF

  • ON: DOME CUT relay off (interior lights turn off)
  • OFF: DOME CUT relay on (interior lights turn on)
Body Electrical > Main Body > Active Test

Tester Display

Relay for Interior Light Auto Cut Function

OK:

All of the interior lights turn off when ON is selected.

OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

2.

CHECK HARNESS AND CONNECTOR (POWER SOURCE - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

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

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

2E-1 - Body ground

Always

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.

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 voltage and resistance according to the value(s) in the table below.

*a

Component without harness connected

(Instrument Panel Junction Block Assembly)

-

-

Standard Voltage:

Tester Connection

Condition

Specified Condition

2D-19 - Battery negative terminal

Battery positive (+) → 2E-1

Battery negative (-) → MB-23 (DOMR)

11 to 14 V

2B-9 - Battery negative terminal

Battery positive (+) → 2E-1

Battery negative (-) → MB-23 (DOMR)

11 to 14 V

2B-10 - Battery negative terminal

Battery positive (+) → 2E-1

Battery negative (-) → MB-23 (DOMR)

11 to 14 V

Standard Resistance:

Tester Connection

Condition

Specified Condition

2E-1 - 2D-19

Always

10 kΩ or higher

2E-1 - 2B-9

Always

10 kΩ or higher

2E-1 - 2B-10

Always

10 kΩ or higher

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

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    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual

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