Lexus IS250 · Service Manual BODY ELECTRICAL

Interior Light Switch Signal Circuit

Circuit diagnosis

DESCRIPTION

The main body ECU RH receives information on the front interior light switch (marked ON/OFF).
The main body ECU LH receives information on the front interior light switch (marked DOOR).
According to the position of each switch, the main body ECU RH controls the turning on and off of the interior lights, and the main body ECU LH controls the illuminated entry system.

WIRING DIAGRAM

E123465E03

INSPECTION PROCEDURE


1. READ VALUE OF 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 DATA LIST, and read the display on the intelligent tester.

    DATA LIST: Main Body (Main Body ECU RH) 
    Item
    		 Measurement Item / Display
    (Range)
    		 Normal Condition
    		 Diagnostic Note
    Illumination SW
    		 Front interior light switch (marked ON/OFF) signal/ ON or OFF
    		 ON: Front interior light switch (marked ON/OFF) is pushed in
    OFF: Front interior light switch (marked ON/OFF) is not pushed in
    		 -
    DATA LIST: Body No. 3 (Main Body ECU LH) 
    Item
    		 Measurement Item / Display
    (Range)
    		 Normal Condition
    		 Diagnostic Note
    Interior Light
    		 Front interior light switch (marked DOOR) signal/ ON or OFF
    		 ON: Front interior light switch (marked DOOR) is pushed in
    OFF: Front interior light switch (marked DOOR) is not pushed in
    		 -

    OK:
    Switch condition can be displayed.


    Result:
    Result
    		 Proceed to
    Indication for "ILLUMI SW" does not change
    		 A
    Indication for "INTERIOR LIGHT" does not change
    		 B
    Indications for both "ILLUMI SW" and "INTERIOR LIGHT" do not change
    		 C
    OK
    		 D



A
Go to step 2

B
Go to step 4

C
Go to step 6
D

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

2. INSPECT OVERHEAD J/B

  1. E123250E03
    Remove the overhead J/B.

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

    Standard resistance:
    Tester Connection
    		 Switch Condition
    		Specified Condition
    R5-34 (CILL) - R5-18 (GND3)
    		Front interior light switch (marked ON/OFF) is not pushed in
    		 10 kΩ or higher
    R5-34 (CILL) - R5-18 (GND3)
    		Front interior light switch (marked ON/OFF) is pushed in
    		 Approx. 10 Ω



NG
REPLACE OVERHEAD J/B
OK


3. CHECK HARNESS AND CONNECTOR (OVERHEAD J/B - MAIN BODY ECU RH)

  1. E123251E03
    Disconnect the R5 overhead J/B connector.

  1. Disconnect the J75 main body ECU RH connector.

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

    Standard resistance:
    Tester Connection
    		 Condition
    		Specified Condition
    R5-34 (CILL) - J75-4 (UL2)
    		 Always
    		 Below 1 Ω
    R5-34 (CILL) - Body ground
    		Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

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

4. INSPECT OVERHEAD J/B

  1. E123250E04
    Remove the overhead J/B.

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

    Standard resistance:
    Tester Connection
    		 Switch Condition
    		Specified Condition
    R5-35 (DOOR) - R5-18 (GND3)
    		 Front interior light switch (marked DOOR) is not pushed in
    		 10 kΩ or higher
    R5-35 (DOOR) - R5-18 (GND3)
    		Front interior light switch (marked DOOR) is pushed in
    		 Approx. 10 Ω



NG
REPLACE OVERHEAD J/B
OK


5. CHECK HARNESS AND CONNECTOR (OVERHEAD J/B - MAIN BODY ECU LH)

  1. E125498E01
    Disconnect the R5 overhead J/B connector.

  1. Disconnect the J75 main body ECU LH connector.

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

    Standard resistance:
    Tester Connection
    		 Condition
    		Specified Condition
    R5-35 (DOOR) - Q3-11 (BDCY)
    		 Always
    		 Below 1 Ω
    R5-35 (DOOR) - 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)

6. INSPECT OVERHEAD J/B

  1. E123250E05
    Remove the overhead J/B.

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

    Standard resistance:
    Tester Connection
    		 Switch Condition
    		Specified Condition
    R5-35 (DOOR) - R5-18 (GND3)
    		 Front interior light switch (marked DOOR) is not pushed in
    		 10 kΩ or higher
    R5-35 (DOOR) - R5-18 (GND3)
    		Front interior light switch (marked DOOR) is pushed in
    		 Approx. 10 Ω
    R5-34 (CILL) - R5-18 (GND3)
    		Front interior light switch (marked ON/OFF) is not pushed in
    		 10 kΩ or higher
    R5-34 (CILL) - R5-18 (GND3)
    		Front interior light switch (marked ON/OFF) is pushed in
    		 Approx. 10 Ω



NG
REPLACE OVERHEAD J/B
OK

REPAIR OR REPLACE HARNESS OR CONNECTOR (OVERHEAD J/B GROUND CIRCUIT)


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