Lexus IS250 · Service Manual BODY ELECTRICAL

Door Mirror Foot Light Circuit

Circuit diagnosis

DESCRIPTION

The turning on and off of the door mirror foot lights is controlled by the main body 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 door mirror foot lights in and out by duty control.
This MOS-FET circuit has an overheat protection function as a fail-safe. If the main body ECU LH becomes excessively hot, the door mirror foot lights turn off and remain off.
Normal operation will resume when the conditions required to turn on the door mirror foot lights are met again.

WIRING DIAGRAM

E123475E01

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 main switch 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
    Exterior Foot Light Operation
    Door mirror foot lights ON / OFF
    -

    OK:
    Door mirror foot lights come on.

    HINT:
    The door mirror foot lights RH and LH share the same power source. If either of the lights does not come on, there may be a problem in the part of the circuit that relates to that light. Therefore, inspect that part of the circuit.



NG
Go to step 2
OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

2. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU LH - BATTERY)

  1. E123248E04
    Disconnect the Q1 main body ECU LH connector.

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

    Standard voltage:
    Tester Connection
    Condition
    Specified Condition
    Q1-4 (LCTY) - 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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