Toyota Yaris: Lighting System / Interior Light Auto Cut Circuit

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

DESCRIPTION

The main body ECU (multiplex network body ECU) controls operation of the DOME CUT relay in order to supply power to the interior lights. When the battery saving function operates while the interior lights are on, the main body ECU (multiplex network body ECU) opens the DOME CUT relay to turn off the lights.

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
Relay for Interior Light Auto Cut Function	DOME CUT relay	OFF or ON	When performing this Active Test, turn all the interior lights on. OFF: DOME CUT relay on (interior lights turn on) ON: DOME CUT relay off (interior lights turn off)

Body Electrical > Main Body > Active Test

Tester Display
Relay for Interior Light Auto Cut Function

OK:

All of the interior lights turn off when ON is selected.

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
4C-4 - Auxiliary battery negative (-)	Auxiliary battery positive (+) → 4F-1 Auxiliary battery negative (-) → MB-17 (DOMR)	11 to 14 V
4E-20 - Auxiliary battery negative (-)	Auxiliary battery positive (+) → 4F-1 Auxiliary battery negative (-) → MB-17 (DOMR)	11 to 14 V

Tester Connection

Condition

Specified Condition

4C-4 - Auxiliary battery negative (-)

Auxiliary battery positive (+) → 4F-1

Auxiliary battery negative (-) → MB-17 (DOMR)

11 to 14 V

4E-20 - Auxiliary battery negative (-)

Auxiliary battery positive (+) → 4F-1

Auxiliary battery negative (-) → MB-17 (DOMR)

11 to 14 V

Standard Resistance:

Tester Connection	Condition	Specified Condition
4F-1 - 4C-4	Always	10 kΩ or higher
4F-1 - 4E-20	Always	10 kΩ or higher

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

REPLACE POWER DISTRIBUTION BOX ASSEMBLY

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