Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: LED Headlight LH (B2430,B2431)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Exterior / Lighting (ext) / Lighting System (w/o Automatic Headlight Beam Level Control System) / LED Headlight LH (B2430,B2431)

DESCRIPTION

These DTCs are stored when the low beam headlights do not illuminate, or a communication malfunction is detected between the headlight assembly and main body ECU (multiplex network body ECU).

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

DTC Output from

B2430

LED Headlight LH
  • All of the following conditions are met:
    • Engine running
    • Low beam headlights on
  • Any of the following conditions is met:
    • Headlight assembly LH malfunction
    • Headlight assembly LH power source and signal malfunction
  • 12 seconds or more
  • Headlight assembly LH
  • Semiconductor power integration ECU
  • Instrument panel junction block assembly
  • Main body ECU (multiplex network body ECU)
  • Harness or connector

Main Body

B2431

LED Headlight RH
  • All of the following conditions are met:
    • Engine running
    • Low beam headlights on
  • Any of the following conditions is met:
    • Headlight assembly RH malfunction
    • Headlight assembly RH power source and signal malfunction
  • 12 seconds or more
  • Headlight assembly RH
  • Semiconductor power integration ECU
  • Instrument panel junction block assembly
  • Main body ECU (multiplex network body ECU)
  • Harness or connector

Main Body

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.

CLEAR DTC

(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 / Trouble Codes.

(e) Clear the DTCs.

Body Electrical > Main Body > Clear DTCs
NEXT

2.

CHECK FOR DTC

(a) Connect the Techstream to the DLC3.

(b) Start the engine.

(c) Operate the light control switch to turn on the low beam headlights and wait 12 seconds or more.

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Main Body / Trouble Codes.

(f) Check for DTCs.

Body Electrical > Main Body > Trouble Codes

OK:

DTC B2430 and B2431 are not output.

Result

Proceed to

Both DTC B2430 and B2431 are not output

A

Both DTC B2430 and B2431 are output

B

Only DTC B2430 or B2431 is output

C
A

USE SIMULATION METHOD TO CHECK

C

GO TO STEP 7

B

3.

INSPECT SEMICONDUCTOR POWER INTEGRATION ECU

(a) Remove the semiconductor power integration ECU from the engine room relay block and junction block assembly.

Click here

(b) Inspect the semiconductor power integration ECU.

Click here

OK:

Semiconductor power integration ECU is normal.

NG

REPLACE SEMICONDUCTOR POWER INTEGRATION ECU

OK

4.

CHECK HARNESS AND CONNECTOR (POWER SOURCE - SEMICONDUCTOR POWER INTEGRATION ECU)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

B-1 (BATT) - Body ground

Always

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

5.

CHECK HARNESS AND CONNECTOR (SEMICONDUCTOR POWER INTEGRATION ECU - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

(a) Disconnect the 2C 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

1D-8 - 2C-31

Always

Below 1 Ω

1D-8 or 2C-31 - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

6.

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

*a

Component without harness connected

(Instrument Panel Junction Block Assembly)

-

-

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

Click here

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2C-31 - MB-15 (HRLY)

Always

Below 1 Ω
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

7.

INSPECT SEMICONDUCTOR POWER INTEGRATION ECU

(a) Remove the semiconductor power integration ECU from the engine room relay block and junction block assembly.

Click here

(b) Inspect the semiconductor power integration ECU.

Click here

OK:

Semiconductor power integration ECU is normal.

NG

REPLACE SEMICONDUCTOR POWER INTEGRATION ECU

OK

8.

CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY LO TERMINAL VOLTAGE)

(a) Disconnect the A20 headlight assembly LH connector.

*A

for LH Side

*B

for RH Side

*a

Front view of wire harness connector

(to Headlight Assembly)

(b) Disconnect the A24 headlight assembly RH connector.

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

Standard Voltage:

for LH Side

Tester Connection

Condition

Specified Condition

A20-5 (LO) - Body ground

Light control switch in head position

11 to 14 V
for RH Side

Tester Connection

Condition

Specified Condition

A24-5 (LO) - Body ground

Light control switch in head position

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

9.

CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY - BODY GROUND)

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

Standard Resistance:

for LH Side

Tester Connection

Condition

Specified Condition

A20-6 (E) - Body ground

Always

Below 1 Ω
for RH Side

Tester Connection

Condition

Specified Condition

A24-6 (E) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

10.

CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY S TERMINAL VOLTAGE)

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

Standard Voltage:

for LH Side

Tester Connection

Condition

Specified Condition

A20-7 (S) - Body ground

Light control switch in head position

11 to 14 V
for RH Side

Tester Connection

Condition

Specified Condition

A24-7 (S) - Body ground

Light control switch in head position

11 to 14 V

*A

for LH Side

*B

for RH Side

*a

Front view of wire harness connector

(to Headlight Assembly)

Result

Proceed to

OK (for TMC Made)

A

OK (for TMMC Made)

B

NG

C
A

REPLACE HEADLIGHT UNIT

B

REPLACE HEADLIGHT ASSEMBLY

C

11.

CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU))

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

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

Standard Voltage:

for LH Side

Tester Connection

Condition

Specified Condition

A20-7 (S) - J8-16 (LLEW)

Always

Below 1 Ω

A20-7 (S) or J8-16 (LLEW) - Body ground

Always

10 kΩ or higher
for RH Side

Tester Connection

Condition

Specified Condition

A24-7 (S) - J8-3 (RLEW)

Always

Below 1 Ω

A24-7 (S) or J8-3 (RLEW) - Body ground

Always

10 kΩ or higher
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
    Automatic High Beam Camera (B124C)
    DESCRIPTION The main body ECU (multiplex network body ECU) detects a high beam headlight illumination request signal of the automatic high beam system from the forward recognition camera. DTC No. ...

    Lost Communication With ECM/PCM "A" Missing Message (U010087,U012587,U012987,U014087)
    DESCRIPTION These DTCs are stored if a CAN communication malfunction occurs between the forward recognition camera and other ECUs. DTC No. Detection Item DTC Detection Condition Trouble Area ...

    Other materials:

    Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Lane Control System: Fail-safe Chart
    FAIL-SAFE CHART FAIL-SAFE FUNCTION (a) When a malfunction occurs in the lane control system, a message will be displayed on the multi-information display and, depending on the malfunction, functions of the lane control system will be disabled. Warning Message Cause Fail-safe Operation Condi ...

    Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Safety Connect System: Acn Call End
    ACN CALL END ACN CALL END This function terminates the ACN (Automatic Collision Notification) to the telematics provider. After a collision in which the DCM receives "Collision Detection Signal", the vehicle will send the emergency call notification to the telematics provider until the emergency cal ...

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

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

    © 2025 Copyright www.lexusrx.net
    0.0114