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
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