Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Open in IG Circuit (B242E)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Exterior / Lighting (ext) / Lighting System (w/ Automatic Headlight Beam Level Control System) / Open in IG Circuit (B242E)

DESCRIPTION

The No. 1 headlight ECU sub-assembly operates using the power source voltage input from the IG terminal and ECUB terminal.

The IG terminal power source voltage is supplied by turning the IG1 relay to ON.

The No. 1 headlight ECU sub-assembly receives engine switch on (IG) signals from the main body ECU (multiplex network body ECU) via CAN communication, compares the engine switch on (IG) signal and the power source voltage supply condition of the IG terminal and monitors the result.

for Multiple Beam Headlight

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

DTC Output from

B242E

Open in IG Circuit
  • The engine switch is on (IG).
  • When the IG terminal power source voltage is 0 V (engine switch off), IG ON signals from the main body ECU (multiplex network body ECU) via CAN communication are continuously received
  • 10 seconds or more
  • No. 1 headlight ECU sub-assembly LH
  • Harness or connector

AFS
for Single Beam Headlight

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

DTC Output from

B242E

Open in IG Circuit
  • The engine switch is on (IG).
  • When the IG terminal power source voltage is 0 V (engine switch off), IG ON signals from the main body ECU (multiplex network body ECU) via CAN communication are continuously received
  • 10 seconds or more
  • No. 1 headlight ECU sub-assembly LH
  • Harness or connector

HL AutoLeveling

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • If the No. 1 headlight ECU sub-assembly LH has been replaced, it is necessary to synchronize the vehicle information and initialize the No. 1 headlight ECU sub-assembly LH.

    Click here

  • If the headlight assembly LH has been replaced, it is necessary to synchronize the vehicle information and initialize the No. 1 headlight ECU sub-assembly LH.*

    Click here

  • When replacing the No. 1 headlight ECU sub-assembly LH, always replace it with a new one. If a No. 1 headlight ECU sub-assembly LH which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.
  • When replacing the headlight assembly LH, always replace it with a new one. If a headlight assembly LH which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.*
    • *: for TMMC Made

PROCEDURE

1.

CONFIRM MODEL

(a) Choose the model to be inspected.

Result

Proceed to

for Multiple Beam Headlight

A

for Single Beam Headlight

B
B

GO TO STEP 4

A

2.

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 / AFS / Trouble Codes.

(e) Clear the DTCs.

Body Electrical > AFS > Clear DTCs
NEXT

3.

CHECK FOR DTC

(a) Connect the Techstream to the DLC3.

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

(c) Wait 10 seconds or more.

(d) Turn the Techstream on.

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

(f) Check for DTCs.

Body Electrical > AFS > Trouble Codes

OK:

DTC B242E is not output.

OK

USE SIMULATION METHOD TO CHECK

NG

GO TO STEP 6

4.

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 / HL AutoLeveling / Trouble Codes.

(e) Clear the DTCs.

Body Electrical > HL AutoLeveling > Clear DTCs
NEXT

5.

CHECK FOR DTC

(a) Connect the Techstream to the DLC3.

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

(c) Wait 10 seconds or more.

(d) Turn the Techstream on.

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

(f) Check for DTCs.

Body Electrical > HL AutoLeveling > Trouble Codes

OK:

DTC B242E is not output.

OK

USE SIMULATION METHOD TO CHECK

NG

6.

INSPECT NO. 1 HEADLIGHT ECU SUB-ASSEMBLY LH (IG TERMINAL VOLTAGE)

*a

Front view of wire harness connector

(to No. 1 Headlight ECU Sub-assembly LH)

(a) Disconnect the A49 No. 1 headlight ECU sub-assembly LH connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A49-4 (IG) - Body ground

Engine switch on (IG)

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

7.

CHECK HARNESS AND CONNECTOR (NO. 1 HEADLIGHT ECU SUB-ASSEMBLY LH - BODY GROUND)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A49-12 (GND) - Body ground

Always

Below 1 Ω
OK

REPLACE NO. 1 HEADLIGHT ECU SUB-ASSEMBLY LH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
    Right Headlight ECU Malfunction (B242C,B242D)
    DESCRIPTION The No. 1 headlight ECU sub-assembly LH stores a DTC if it detects an internal malfunction. for Multiple Beam Headlight DTC No. Detection Item DTC Detection Condition Trouble Area ...

    Left Low Beam Fan Malfunction (B243D,B243E)
    DESCRIPTION The No. 1 headlight ECU sub-assembly operates the low beam fan to cool the headlight LED unit in order to prevent the headlight LED unit from overheating. Illuminates the low beam headligh ...

    Other materials:

    Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Smart Access System With Push-button Start (for Entry Function): Open in Driver Side Electrical Antenna Circuit (B27A1)
    DESCRIPTION The certification ECU (smart key ECU assembly) generates a request signal and transmits the signal to the front door outside handle assembly (for driver door) (electrical key antenna) at intervals of 0.25 seconds. For the front door outside handle assembly (for driver door) (electrical k ...

    Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Audio And Visual System (for 8 Inch Display): Cellular Phone Inspection
    PROCEDURE 1. CHECK USAGE CONDITION (a) Check that the vehicle and cellular phone meet the following conditions: NOTICE: If changing cellular phone settings, updating software, etc. is necessary, make sure to obtain the permission of the customer before performing it. The cellular phone i ...

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

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

    © 2025 Copyright www.lexusrx.net
    0.015