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

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Exterior / Lighting (ext) / Lighting System (w/ Automatic Headlight Beam Level Control System) / Front Side Marker Light Circuit

DESCRIPTION

When the light control switch is in the tail or head position, the main body ECU (multiplex network body ECU) sends an illumination request signal to the No. 1 headlight ECU sub-assembly to illuminate the front side marker lights.

WIRING DIAGRAM

for Multiple Beam Headlight

for Single Beam Headlight

CAUTION / NOTICE / HINT

NOTICE:

  • 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.*1

    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.*1
  • Inspect the front side marker light bulb before performing the following procedure.*2
    • *1: for TMMC Made
    • *2: for Single Beam Headlight

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 3

A

2.

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 / AFS / Active Test.

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

Body Electrical > AFS > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Clearance Light

Parking lights

OFF or ON

-
Body Electrical > AFS > Active Test

Tester Display

Clearance Light

OK:

Front side marker light illuminate.

Result

Proceed to

OK

A

NG (LH side front side marker light does not illuminate)

B

NG (RH side front side marker light does not illuminate)

C
A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

B

GO TO STEP 4

C

GO TO STEP 6

3.

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 / HL AutoLeveling / Active Test.

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

Body Electrical > HL AutoLeveling > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Clearance Light

Parking lights

OFF or ON

-
Body Electrical > HL AutoLeveling > Active Test

Tester Display

Clearance Light

OK:

Front side marker light illuminate.

Result

Proceed to

OK

A

NG (LH side front side marker light does not illuminate)

B

NG (RH side front side marker light does not illuminate)

C
A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

C

GO TO STEP 6

B

4.

CHECK HEADLIGHT UNIT LH

(a) Interchange the headlight unit LH with RH and connect the connectors.

Click here

NEXT

5.

CHECK OPERATION (FRONT SIDE MARKER LIGHT)

(a) Check that the front side marker light operates normally.

OK:

Front side marker light operates normally.

Result

Proceed to

OK

A

NG (for TMC Made)

B

NG (for TMMC Made)

C
A

REPLACE NO. 1 HEADLIGHT ECU SUB-ASSEMBLY LH

B

REPLACE HEADLIGHT UNIT LH

C

REPLACE HEADLIGHT ASSEMBLY LH

6.

CHECK HEADLIGHT UNIT RH

(a) Interchange the headlight unit RH with LH and connect the connectors.

Click here

NEXT

7.

CHECK OPERATION (FRONT SIDE MARKER LIGHT)

(a) Check that the front side marker light operates normally.

OK:

Front side marker light operates normally.

Result

Proceed to

OK

A

NG (for TMC Made)

B

NG (for TMMC Made)

C
A

REPLACE NO. 1 HEADLIGHT ECU SUB-ASSEMBLY RH

B

REPLACE HEADLIGHT UNIT RH

C

REPLACE HEADLIGHT ASSEMBLY RH

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