Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Parking Light/Daytime Running Light Circuit

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

DESCRIPTION

Parking light function:
  • When the main body ECU (multiplex network body ECU) receives the light control switch position signal, it sends an illumination request signal to the No. 1 headlight ECU sub-assembly and illuminates the parking lights.
Daytime running light function:
  • When the operation conditions of the daytime running lights are met, the main body ECU (multiplex network body ECU) sends an illumination request signal to the No. 1 headlight ECU sub-assembly and illuminates the daytime running 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.*

    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 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

-

Daytime Running Light

Daytime running lights

OFF or ON

This Active Test can only be performed when the customization item DRL function is set to "ON" using the Techstream.
Body Electrical > AFS > Active Test

Tester Display

Clearance Light
Body Electrical > AFS > Active Test

Tester Display

Daytime Running Light

OK:

Parking lights and daytime running lights illuminate.

Result

Proceed to

OK

A

NG (LH side parking light and daytime running light does not illuminate)

B

NG (RH side parking light and daytime running 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

-

Daytime Running Light

Daytime running lights

OFF or ON

This Active Test can only be performed when the customization item DRL function is set to "ON" using the Techstream.
Body Electrical > HL AutoLeveling > Active Test

Tester Display

Clearance Light
Body Electrical > HL AutoLeveling > Active Test

Tester Display

Daytime Running Light

OK:

Parking lights and daytime running lights illuminate.

Result

Proceed to

OK

A

NG (LH side parking light and daytime running light does not illuminate)

B

NG (RH side parking light and daytime running 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 (PARKING LIGHTS AND DAYTIME RUNNING LIGHTS)

(a) Check the operation of the parking lights and daytime running lights.

OK:

The parking lights and daytime running lights operate 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 (PARKING LIGHTS AND DAYTIME RUNNING LIGHTS)

(a) Check the operation of the parking lights and daytime running lights.

OK:

The parking lights and daytime running lights operate 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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