Lexus IS250 · Service Manual BODY ELECTRICAL

Scuff Plate Light Circuit

Circuit diagnosis

DESCRIPTION

The operation timing of the scuff plate lights is the same as that of the front and rear interior lights.
The scuff plate lights turn on when a door is opened, and turn off when the door is closed. This illumination setting can be canceled using the overhead J/B switch.
In addition, the scuff plate lights blink while the theft deterrent system is sounding an alarm.
The turning on and off of the scuff plate lights is controlled by the main body ECU LH based on various signals received through BEAN communication.
The main body ECU LH includes a MOS-FET (Metal Oxide Semiconductor - Field Effect Transistor) circuit that fades the scuff plate lights in and out by duty control.
This MOS-FET circuit has an overheat protection function as fail-safe. If the main body ECU LH becomes excessively hot, the scuff plate lights turn off and remain off.
Normal operation will resume when the conditions required to turn on the scuff plate lights are met again.

WIRING DIAGRAM

E123482E01

INSPECTION PROCEDURE


1. PERFORM ACTIVE TEST BY INTELLIGENT TESTER
  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Turn the intelligent tester on.

  1. Select the item(s) in the ACTIVE TEST, and check the operation.

    ACTIVE TEST: Body No. 3 (Main body ECU LH) 
    Item
    Test Details
    Diagnostic Note
    Interior Light Operation
    Interior light ON / OFF
    -

    OK:
    The scuff plate light LH and RH come on.


    Result:
    Result
    Proceed to
    Scuff plate light LH does not come on
    A
    Scuff plate light RH light does not come on
    B
    Neither LH nor RH light comes on
    C
    OK
    D



B
Go to step 5

C
Go to step 8

D
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
A


2. INSPECT SCUFF PLATE LIGHT (FRONT LH)

  1. E073248E02
    Remove the scuff plate light.

  1. Connect the (+) lead from the battery to terminal 2 and the (-) lead to terminal 1, and then check that the scuff plate light comes on.

    OK:
    The scuff plate light comes on.



NG
REPLACE SCUFF PLATE LIGHT
OK


3. CHECK HARNESS AND CONNECTOR (SCUFF PLATE LIGHT - BODY GROUND)

  1. E068686E03
    Disconnect the Q8 scuff plate light connector.

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

    Standard voltage:
    Tester Connection
    Condition
    Specified Condition
    Q8-2 (+) - Body ground
    Always
    10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


4. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU LH - SCUFF PLATE LIGHT)

  1. E123254E03
    Disconnect the Q8 scuff plate light connector.

  1. Disconnect the LA main body ECU LH connector.

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

    Standard resistance:
    Tester Connection
    Condition
    Specified Condition
    LA-19 (ILE1) - Q8-1 (-)
    Always
    Below 1 Ω
    LA-19 (ILE1) - Body ground
    Always
    10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE MAIN BODY ECU LH (COWL SIDE J/B LH)

5. INSPECT SCUFF PLATE LIGHT (FRONT RH)

  1. E123255E04
    Remove the scuff plate light.

  1. Connect the (+) lead from the battery to terminal 2 and the (-) lead to terminal 1, and then check that the scuff plate light comes on.

    OK:
    The scuff plate light comes on.



NG
REPLACE SCUFF PLATE LIGHT
OK


6. CHECK HARNESS AND CONNECTOR (SCUFF PLATE LIGHT - BODY GROUND)

  1. E068686E04
    Disconnect the P2 scuff plate light connector.

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

    Standard voltage:
    Tester Connection
    Condition
    Specified Condition
    P2-2 (+) - Body ground
    Always
    10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


7. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU LH - SCUFF PLATE LIGHT)

  1. E123254E04
    Disconnect the P2 scuff plate light connector.

  1. Disconnect the LA main body ECU LH connector.

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

    Standard resistance:
    Tester Connection
    Condition
    Specified Condition
    LA-19 (ILE1) - P2-1 (-)
    Always
    Below 1 Ω
    LA-19 (ILE1) - Body ground
    Always
    10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE MAIN BODY ECU LH (COWL SIDE J/B LH)

8. CHECK HARNESS AND CONNECTOR (POWER SOURCE OF SCUFF PLATE LIGHT)

HINT:
  1. If neither of the scuff plate lights comes on as a result of the ACTIVE TEST, there may be problems in the power source and main body ECU LH.
  2. Perform the following inspection on either the LH or RH side.

  1. E123255E03
    Disconnect the Q8 or P2 scuff plate light connector.

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

    Standard voltage:
    Front Door RH:
    Tester Connection
    Condition
    Specified Condition
    Q8-2 (+) - Body ground
    Always
    10 to 14 V
    Front Door LH:
    Tester Connection
    Condition
    Specified Condition
    P2-2 (+) - Body ground
    Always
    10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE MAIN BODY ECU LH (COWL SIDE J/B LH)


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