Toyota Yaris: Meter / Gauge System / Meter Illumination does not Dim at Night

Toyota Yaris XP210 (2020-2025) Reapir and Service Manual / Vehicle Interior / Meter / Gauge / Display / Meter / Gauge System / Meter Illumination does not Dim at Night

DESCRIPTION

In this circuit, the combination meter assembly receives auto dimmer signals from the main body ECU (multiplex network body ECU) via CAN communication. When the combination meter assembly receives an auto dimmer signal, it dims the meter illumination (warning and indicator lights).

The main body ECU (multiplex network body ECU) determines whether it is daytime or nighttime based on the waveform transmitted from the automatic light control sensor. If the main body ECU (multiplex network body ECU) determines that it is nighttime and the light control switch is in the tail, head, or AUTO position, the ECU sends an auto dimmer signal to the combination meter assembly.

According to this signal, the combination meter assembly dims the meter illumination.

HINT:

When the meter illumination does not dim at night, there may be a malfunction in the automatic light control sensor, main body ECU (multiplex network body ECU), CAN communication system, wire harness, connector, or combination meter assembly.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Before replacing the main body ECU (multiplex network body ECU), refer to Registration.
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When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.

HINT:

Setting the meter illumination level to maximum brightness prevents the meter illumination from dimming when the light control switch is changed to the tail, head or AUTO position at night. Therefore, check the meter illumination setting before proceeding to the following steps.
The automatic light control sensor sensitivity can be customized.
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PROCEDURE

1.	CHECK CAN COMMUNICATION SYSTEM

(a) Check if CAN communication DTCs are output.

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Result	Proceed to
DTCs are not output	A
DTCs are output	B

GO TO CAN COMMUNICATION SYSTEM

2.	CHECK FOR DTC (LIGHTING SYSTEM)

(a) Check if lighting system DTCs are output.

Body Electrical > Main Body > Trouble Codes

OK:

DTC B124400 is not output.

GO TO DTC B124400

3.	CHECK COMBINATION METER ASSEMBLY

(a) Replace the combination meter assembly with a new one.

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(b) Check the operation.

OK:

The operation of the combination meter assembly returns to normal.

END (COMBINATION METER ASSEMBLY IS DEFECTIVE)

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

Meter Illumination is Always Dark

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