METER / GAUGE SYSTEM Meter Illumination does not Dim at Night

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.

Tech Tips

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

A003W1GE28

INSPECTION PROCEDURE

Tech Tips


  • The automatic light control sensor sensitivity can be customized Click here.


  • 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.


  • Before starting following inspection, check if the lighting system outputs the DTCs Click here.

PROCEDURE


  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.

    2. Turn the power switch on (IG).

    3. Turn the intelligent tester on.

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

    5. 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.

      Tech Tips

      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