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

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

DESCRIPTION

The main body ECU (multiplex network body ECU) controls the operation of the following lights:

  • Map Light Assembly (Front Dome Light)
  • Spot Light Assembly (Rear Dome Light)
  • Front Door Scuff Plate LH (Scuff Light LH)(w/ Scuff Light)
  • Front Door Scuff Plate RH (Scuff Light RH)(w/ Scuff Light)

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

    Click here

HINT:

The DOME CUT relay supplies power to the interior lights. If all the lights that use power from the DOME CUT relay do not turn on, check the interior light auto cut circuit first.

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

Illuminated Entry System

Turns on the lights that are controlled by the illuminated entry system*1

ON or OFF

Perform the Active Test with door switch in the map light assembly turned on.
  • *1: Refer to Description for the lights that are controlled by the illuminated entry system.

    Click here

Body Electrical > Main Body > Active Test

Tester Display

Illuminated Entry System
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

2.

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

2B-29 - MB-1 (ILE)

Always

Below 1 Ω
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

    Back Door Courtesy Switch Circuit
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    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 ...

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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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