Lexus IS250 IS220d GSE20 ALE20 - LIGHTING

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK PERSONAL LIGHT (OPERATION)

PERFORM ACTIVE TEST BY INTELLIGENT TESTER

INSPECT REAR DOME LIGHT ASSEMBLY (REAR SEAT ILLUMINATION)

CHECK HARNESS AND CONNECTOR (OVERHEAD J/B - REAR DOME LIGHT ASSEMBLY)

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

CHECK HARNESS AND CONNECTOR (POWER SOURCE)

LIGHTING SYSTEM - Seat Illumination Circuit

DESCRIPTION

The seat illumination can be canceled using the overhead J/B switch.

The turning on and off of the seat illumination 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 seat illumination 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 seat illumination turns off and remains off.

Normal operation will resume when the conditions required to turn on the seat illumination are met again.

WIRING DIAGRAM

Lighting System - Seat Illumination Circuit. LIGHTING. Lexus IS250 IS220d GSE20 ALE20

INSPECTION PROCEDURE

1.CHECK PERSONAL LIGHT (OPERATION)

HINT:

The personal lights and seat illumination share the same power source circuit. Therefore, if none of them come on, inspect the power source circuit first.

Push the personal light switches.

Check that the personal lights come on.

OK:
Personal lights come on.

NG

Go to step 7

OK

2.PERFORM ACTIVE TEST BY INTELLIGENT TESTER

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG).

Turn the intelligent tester main switch on.

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

ACTIVE TEST: Body No. 3 (Main Body ECU LH)
Item	Test Details	Diagnostic Note
Interior Light (Dim) Operation	Front and rear seat illumination ON / OFF	-

OK:
Front and rear seat illumination comes on.

Result:
Result Proceed to
Front seat illumination does not come on A
Rear seat illumination does not come on B
Neither front nor rear seat illumination comes on C
OK D

HINT:

If the rear seat illumination comes on normally, but the front seat illumination does not come on, there is an open circuit in the overhead J/B.

A

Go to step 3

C

Go to step 5

D

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

3.INSPECT REAR DOME LIGHT ASSEMBLY (REAR SEAT ILLUMINATION)

Lighting System - Seat Illumination Circuit. LIGHTING. Lexus IS250 IS220d GSE20 ALE20

Remove the rear dome light assembly.

Connect the (+) lead from the battery to terminal 2 and the (-) lead to terminal 5, and then check that the seat illumination comes on.

OK:
Seat illumination comes on.

NG

Go to step 6

OK

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

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

Disconnect the Q3 main body ECU LH connector.

Disconnect the R5 overhead J/B connector.

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

Standard resistance:
Tester Connection Condition Specified Condition
Q3-3 (LGCY) - R5-12 (CTY) Always Below 1 Ω
Q3-3 (LGCY) - Body ground Always 10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

REPLACE OVERHEAD J/B

7.CHECK HARNESS AND CONNECTOR (POWER SOURCE)