Toyota Yaris: Lighting System / Ambient Illumination Light Circuit

Toyota Yaris XP210 (2020-2025) Reapir and Service Manual / Vehicle Interior / Lighting (int) / Lighting System / Ambient Illumination Light Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) controls the operation of the following lights:

Front Door Ambient Illumination Light
- Front Door Ambient Illumination Light LH (Front Door Trim Board Sub-assembly LH)
- Front Door Ambient Illumination Light RH (Front Door Trim Board Sub-assembly RH)

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.
Before replacing the main body ECU (multiplex network body ECU), refer to Registration.
Click here

PROCEDURE

1.	PERFORM ACTIVE TEST USING GTS

(a) Perform the Active Test according to the display on the GTS.

Body Electrical > Main Body > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
Front Footwell Lights	Front Door Trim Illumination	OFF or ON	*1

*1: w/ Ambient Illumination Light

Body Electrical > Main Body > Active Test

Tester Display
Front Footwell Lights

Result	Proceed to
OK	A
NG (All illuminations do not come on)	B

USE SIMULATION METHOD TO CHECK

2.	CHECK HARNESS AND CONNECTOR (POWER SOURCE - POWER DISTRIBUTION BOX ASSEMBLY)

(a) Disconnect the 4F power distribution box assembly connector.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
4F-1 - Body ground	Ignition switch off	11 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	CHECK POWER DISTRIBUTION BOX ASSEMBLY

Component without harness connected

(Power Distribution Box Assembly)

(a) Disconnect the 4B power distribution box assembly connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
4F-1 - 4B-28	Always	Below 1 Ω

REPLACE POWER DISTRIBUTION BOX ASSEMBLY

4.	INSPECT POWER DISTRIBUTION BOX ASSEMBLY

Component without harness connected

(Power Distribution Box Assembly)

(a) Remove the main body ECU (multiplex network body ECU) from the power distribution box assembly.

Click here

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
4C-18 - MB-16 (FSPT)	Always	Below 1 Ω
4C-19 - MB-16 (FSPT)	Always	Below 1 Ω
4E-22 - MB-16 (FSPT)	Always	Below 1 Ω

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

REPLACE POWER DISTRIBUTION BOX ASSEMBLY

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