METER / GAUGE SYSTEM > Meter Illumination does not Dim at Night

for Preparation Click here


DESCRIPTION

In this circuit, the meter ECU receives auto dimmer signals from the main body ECU (multiplex network body ECU) using the CAN communication system. When the meter ECU 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. 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


E165892E28


INSPECTION PROCEDURE

HINT:
  1. The automatic light control sensor sensitivity can be customized (Click here).
  1. Setting the meter illumination to maximum brightness prevents the meter illumination from dimming when the light control switch is changed to the tail or head position, or changed to the AUTO position at night. Therefore, check the meter illumination setting before proceeding to the following steps.
  1. Before starting following inspection, check if the lighting system outputs the DTCs (Click here).

1.CHECK CAN COMMUNICATION SYSTEM

  1. Check if a CAN communication DTC is output (Click here).

    Result:

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



B
GO TO CAN COMMUNICATION SYSTEM (Click here)
A


2.READ VALUE USING INTELLIGENT TESTER (ILLUMINATION RATE INFO)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the power switch on (IG).

  1. Turn the intelligent tester on.

  1. Enter the following menus: Body / Main Body / Data List.

  1. Check the values by referring to the table below.

    Main Body 
    Tester Display
    		Measurement Item/Range
    		Normal Condition
    		Diagnostic Note
    Illumination Rate Info
    		Illumination rate information/0 ms to 2162.65 ms
    		Value output according to ambient light levels
    		-

    Result:

    Result
    		Proceed to
    The output value changes according to the ambient light levels.
    		A
    The output value does not change according to the ambient light levels.
    		B



B
CHECK LIGHTING SETTING (Click here)
A


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

  1. Replace the main body ECU (multiplex network body ECU) with a new or a known good one (Click here).

    OK:
    The operation of the combination meter assembly returns to normal.

    HINT:
    The meter ECU 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 ECU does not dim the meter illumination even though the meter ECU receives an auto dimmer signal.



NG
REPLACE COMBINATION METER ASSEMBLY (Click here)
OK

END