DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
CHECK SEAT ILLUMINATION (OPERATION)
PERFORM ACTIVE TEST BY INTELLIGENT TESTER
INSPECT REAR DOME LIGHT ASSEMBLY (REAR INTERIOR LIGHT)
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 (MAIN BODY ECU LH - OVERHEAD J/B)
CHECK HARNESS AND CONNECTOR (POWER SOURCE)
LIGHTING SYSTEM - Interior Light Circuit
DESCRIPTION
The Interior 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 interior lights blink while the theft deterrent system is sounding an alarm.
The turning on and off of the interior 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 interior 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 interior lights turn off and remain off.
Normal operation will resume when the conditions required to turn on the interior lights are met again.
If the vehicle is equipped with scuff plate lights, their operation timing is the same as that of the interior lights.
WIRING DIAGRAM
INSPECTION PROCEDURE
| 1.CHECK SEAT ILLUMINATION (OPERATION) |
- The personal lights and interior lights share the same power source. Therefore, if none of them come on, inspect the power source circuit first.
Push the switches for the personal lights.
Check that the personal lights come on.
- OK:
- Personal lights come on.
| 2.PERFORM ACTIVE TEST BY INTELLIGENT TESTER |
Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG).
Turn the intelligent tester 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 Operation |
Interior lights ON / OFF | - |
- OK:
- The front and rear interior lights come on.
- Result:
| Result | Proceed to |
| Front interior light does not come on | A |
| Rear interior light does not come on | B |
| Neither front nor rear interior light comes on | C |
| OK | D |
- If the rear interior light comes on normally, but the front interior light does not come on, there is an open circuit in the overhead J/B.
| D | |
| |
| PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE |
|
| 3.INSPECT REAR DOME LIGHT ASSEMBLY (REAR INTERIOR LIGHT) |
Remove the rear dome light assembly.
Connect the (+) lead from the battery to terminal 2 and the (-) lead to terminal 4, and then check that the interior light comes on.
- OK:
- The interior light comes on.
| 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 Q1 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 |
| Q1-2 (ILE) - R5-13 (ILL) | Always | Below 1 Ω |
| Q1-2 (ILE) - Body ground | Always | 10 kΩ or higher |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
| 7.CHECK HARNESS AND CONNECTOR (POWER SOURCE) |
Disconnect the R5 overhead J/B connector.
Measure the voltage according to the value(s) in the table below.
- Standard voltage:
| Tester Connection | Condition | Specified Condition |
| R5-1 (+B1) - Body ground | Always | 10 to 14 V |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
|
LEXUS IS250, IS220d / GSE20 ALE20
