Toyota Tacoma 2015-2018 Service Manual: Meter Illumination does not Dim at Night

Toyota Tacoma 2015-2018 Service Manual / Meter / Gauge / Display / Meter / Gauge System / Meter Illumination does not Dim at Night

DESCRIPTION

In this circuit, the combination meter assembly auto dimmer signals from the main body ECU using the CAN communication system (CAN V1 Bus). When the combination meter assembly 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, twilight, 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, the ECU sends an auto dimmer signal. According to the 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, harness or connector, or combination meter assembly.

WIRING DIAGRAM

Refer to Meter Illumination is Always Dark (See page ).

CAUTION / NOTICE / HINT

HINT:

The automatic light control sensor sensitiveness can be customized (See page ).

Setting the meter illumination to maximum brightness prevents the meter display 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.

NOTICE:

Recognition code registration is necessary when replacing the main body ECU (multiplex network body ECU).
If the main body ECU (multiplex network body ECU) is replaced, refer to Registration (See page )*1
- *1: w/ Smart Key System

PROCEDURE

1.	CHECK CAN COMMUNICATION SYSTEM

(a) Check if a CAN communication DTC is output (See page Result Result ).

Result

Result	Proceed to
CAN communication DTC is not output	A
CAN communication DTC is output	B

GO TO CAN COMMUNICATION SYSTEM

2.	CONFIRM DTC OUTPUT (LIGHT CONTROL SENSOR CIRCUIT)

(a) Check if DTC B1244 is output (See page ).

Result

Result	Proceed to
B1244 is not output	A
B1244 is output	B

GO TO LIGHTING SYSTEM

3.	CHECK OPERATION (AUTOMATIC LIGHT CONTROL SYSTEM)

(a) Turn the ignition switch to ON.

(b) Turn the light control switch to the AUTO position.

(d) Check that the taillights and low beam headlights.

OK:

The taillights and low beam headlights come on.

(e) Uncover the automatic light control sensor.

(f) Check that the low beam headlights and taillights.

OK:

The low beam headlights and taillights go off.

Result

Result	Proceed to
Automatic light control system operates normally	A
Automatic light control system does not operate normally	B

CHECK LIGHTING SETTING

4.	REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

(a) Replace the main body ECU (multiplex network body ECU) with a new or a normal one (See page OK: ).

OK:

The operation of the combination meter assembly returns to normal.

HINT:

The combination meter assembly controls the meter illumination based on an auto dimmer signal from the main body ECU (multiplex network body ECU). If the meter does not dim when the light control switch is in the tail, head, or AUTO position at night, it may be for either of 2 reasons. The first reason is that the main body ECU (multiplex network body ECU) does not send an auto dimmer signal. The second is that the meter CPU does not dim the meter illumination even though the meter CPU receives an auto dimmer signal.

END (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) WAS DEFECTIVE)

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