Lexus IS250 · Service Manual BODY ELECTRICAL

Illumination Circuit

Circuit diagnosis

DESCRIPTION

Power is supplied to the radio receiver, integration control & panel assembly and steering pad switch assembly illumination when the light control switch is in the TAIL or HEAD position.

WIRING DIAGRAM

E121259E01

INSPECTION PROCEDURE

NOTICE:
The vehicle is equipped with an SRS (Supplemental Restraint System) which includes components such as airbags. Before servicing (including removal or installation of parts), be sure to read the precautionary notice for the supplemental restraint system (Click here).


1. CHECK ILLUMINATION

  1. Check if the illumination for the radio receiver, steering pad switch, integration control & panel assembly, cigarette lighter or others (seat heater switch, hazard switch, etc.) comes on when the light control switch is turned to the HEAD or TAIL position.

    Result:
    Result
    		 Proceed to
    Illumination comes on for all components except steering pad switch.
    		 A
    Illumination comes on for all components except radio receiver.
    		 B
    Illumination comes on for all components except integration control & panel assembly.
    		 C
    No illumination comes on (radio receiver, hazard switch, cigarette lighter, integration control & panel assembly, etc.).
    		 D
    Illumination comes on only for cigarette lighter and steering pad switch.
    		 E



B
Go to step 6

C
Go to step 8

D
GO TO LIGHTING SYSTEM

E
GO TO COMBINATION METER SYSTEM
A


2. CHECK HARNESS AND CONNECTOR (BATTERY - SPIRAL CABLE)

  1. E121218E02
    Disconnect the spiral cable connector.

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

    Standard voltage:
    Tester connection
    		 Condition
    		 Specified condition
    IL+2 - Body ground
    		 Light control SW TAIL or HEAD
    		 10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3. INSPECT STEERING PAD SWITCH ASSEMBLY

  1. Disconnect the steering pad switch assembly connector.

  1. Connect the positive (+) lead to terminal IL+2 and the negative (-) lead to terminal EAU of the steering pad switch assembly connector.E121261E01

  1. Check if the illumination for the steering pad switch assembly comes on.

    OK:
    Illumination for the steering pad switch assembly comes on.



 NG
REPLACE STEERING PAD SWITCH ASSEMBLY
OK


4. INSPECT SPIRAL CABLE

  1. I039337E11
    Disconnect the steering pad switch assembly and spiral cable connectors.

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

    Standard resistance:
    Tester connection
    		 Spiral Cable Position
    		 Specified condition
    EAU - EAU
    		 Center
    		 Below 1 Ω
    2.5 rotations to the left
    2.5 rotations to the right
    IL+2 - IL+2
    		 Center
    		 Below 1 Ω
    2.5 rotations to the left
    2.5 rotations to the right

    NOTICE:
    The spiral cable is an important part of the SRS airbag system. Incorrect removal or installation of the spiral cable may prevent the airbag from deploying. Be sure to read the page shown in the brackets.

    HINT:
    1. Removal (Click here)
    2. Installation (Click here)



 NG
REPLACE SPIRAL CABLE
OK


5. CHECK HARNESS AND CONNECTOR (SPIRAL CABLE - RADIO RECEIVER)

  1. E121260E01
    Disconnect the connectors from the radio receiver and spiral cable.

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

    Standard resistance:
    Tester connection
    		 Condition
    		 Specified condition
    SWG - EAU
    		 Always
    		 Below 1 Ω
    SWG - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE RADIO RECEIVER

6. CHECK HARNESS AND CONNECTOR (BATTERY - RADIO RECEIVER)

  1. E121262E01
    Disconnect the radio receiver connector J66.

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

    Standard voltage:
    Tester connection
    		 Condition
    		 Specified condition
    ILL+ - Body ground
    		 Light control switch TAIL or HEAD
    		 10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


7. CHECK HARNESS AND CONNECTOR (RADIO RECEIVER - COMBINATION METER)

  1. E121263E01
    Disconnect the radio receiver connector and combination meter connector.

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

    Standard resistance:
    Tester connection
    		 Condition
    		 Specified condition
    ILL- - ILL-
    		 Always
    		 Below 1 Ω
    ILL- - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE RADIO RECEIVER

8. CHECK HARNESS AND CONNECTOR (BATTERY - INTEGRATION CONTROL & PANEL ASSEMBLY)

  1. E121264E01
    Disconnect the integration control & panel assembly connector J54.

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

    Standard voltage:
    Tester connection
    		 Condition
    		 Specified condition
    ILL+ - Body ground
    		 Light control switch TAIL or HEAD
    		 10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


9. CHECK HARNESS AND CONNECTOR (INTEGRATION CONTROL & PANEL ASSEMBLY - COMBINATION METER)

  1. E121265E01
    Disconnect the integration control & panel assembly connector and combination meter connector.

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

    Standard resistance:
    Tester connection
    		 Condition
    		 Specified condition
    ILL- - ILL-
    		 Always
    		 Below 1 Ω
    ILL- - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE INTEGRATION CONTROL & PANEL ASSEMBLY


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