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) using the CAN communication system. 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 headlight dimmer switch assembly 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.

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, wire harness, connector, or combination meter assembly.

WIRING DIAGRAM

A01G845E73

INSPECTION PROCEDURE

Note

If the main body ECU (multiplex network body ECU) is replaced, refer to Service Bulletin.

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 headlight dimmer switch assembly is changed to the tail, head, or AUTO position at night. Therefore, check the meter illumination setting before proceeding to the following steps.

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

PROCEDURE


  1. CHECK CAN COMMUNICATION SYSTEM


    1. Check if CAN communication DTCs are output Click here.

      Result
      Result Proceed to
      CAN communication DTCs are not output. A
      CAN communication DTCs are output. B

    B

    GO TO CAN COMMUNICATION SYSTEM Click here

    A

  2. READ VALUE USING GTS (ILLUMINATION RATE INFO)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Body Electrical / 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/0.00 ms. to 2162.65 ms. Value is output according to ambient light levels -
      Result
      Result Proceed to
      The output value changes according to the ambient light level. A
      The output value does not change according to the ambient light level. B

    B

    CHECK CUSTOMIZE PARAMETER SETTING (SENSITIVITY) 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 known good one Click here.

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

      Tech Tips

      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 combination meter assembly does not dim when the headlight dimmer switch assembly is in the tail, head, or AUTO position at night, it may be for one 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 combination meter assembly did not dim the meter illumination even though the combination meter assembly received an auto dimmer signal.


    NG

    REPLACE COMBINATION METER ASSEMBLY Click here

    OK

    END