METER / GAUGE SYSTEM Operating Light Control Rheostat does not Change Light Brightness

DESCRIPTION

In this circuit the meter CPU receives signals for adjusting illumination on the meter. The meter CPU detects the illumination level selected by the user according to the position of the rheostat knob.

Tech Tips


  • This model is equipped with an optitron meter, therefore the meter illuminates even in the daytime.

  • The meter illumination level can be adjusted by turning the rheostat.

  • The meter illumination dims when the light control switch is turned to the TAIL or HEAD position at night.

  • Turning the rheostat knob fully upwards cancels the above dimmer control.

WIRING DIAGRAM

A017GA0E01

INSPECTION PROCEDURE

PROCEDURE


  1. SYSTEM CHECK


    1. Ignition switch on (IG).

    2. Turn the light control rheostat knob fully upwards.

    3. Turn the light control rheostat knob fully downwards.

    4. Turn the light control rheostat knob fully upwards and turn the light control switch to the TAIL or HEAD position.

    5. Check the meter illumination.

      Result
      Result Proceed to
      Meter illumination does not change when operating the light control rheostat knob. A
      Dimmer cancel does not operate (Meter illumination does not dim). B

    B

    READ VALUE USING INTELLIGENT TESTER (TAIL CANCEL SW) Click here

    A

  2. READ VALUE USING INTELLIGENT TESTER (RHEOSTAT)


    1. Connect the intelligent tester to the DLC3.

    2. Ignition switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Body Electrical / Combination Meter / Data List.

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

      Combination Meter:
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Rheostat value Light control rheostat/Min.: 0%, Max.: 100% Light control rheostat switch is Dark (0%) → Bright (100%) -
      OK
      The value displayed on the tester gradually changes with the actual rheostat operation.

    NG

    CHECK HARNESS AND CONNECTOR (COMBINATION METER - LIGHT CONTROL RHEOSTAT) Click here

    OK

  3. READ VALUE USING INTELLIGENT TESTER (TAIL CANCEL SW)


    1. Connect the intelligent tester to the DLC3.

    2. Ignition switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Body Electrical / Combination Meter / Data List.

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

      Combination Meter:
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Tail Cancel SW Tail cancel switch is/ OFF or ON OFF: The light control rheostat knob is not turned fully downwards -
      ON: The light control rheostat knob is turned fully upwards -
      OK
      Condition displayed on the tester is the same as the actual rheostat position.

    NG

    CHECK HARNESS AND CONNECTOR (COMBINATION METER - LIGHT CONTROL RHEOSTAT) Click here

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

  4. CHECK HARNESS AND CONNECTOR (COMBINATION METER - LIGHT CONTROL RHEOSTAT)


    1. A017DKME01

      Disconnect the E1 and D3 connectors.

    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      E1-4 (SW1) - D3-7 (T) Always Below 1 Ω
      E1-24 (SW2) - D3-3 (RV) Always Below 1 Ω
      E1-39 (SW3) - D3-1 (E) Always Below 1 Ω
      D3-1 (E) - Body ground Always 10 kΩ or higher
      D3-3 (RV) - Body ground Always 10 kΩ or higher
      D3-7 (T) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. INSPECT LIGHT CONTROL RHEOSTAT


    1. A017DWQE01

      Remove the light control rheostat with the connector still connected.

    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      D3-1 (E) - D3-3 (RV) Turn the light control rheostat knob fully upwards 8 kΩ or higher
      D3-1 (E) - D3-3 (RV) Rheostat knob position is between MIN. and MAX.

      The value changes gradually

      (Between 1 Ω and 8 kΩ)
      D3-1 (E) - D3-3 (RV) Turn the light control rheostat knob fully downwards Below 1 Ω

    NG

    REPLACE LIGHT CONTROL RHEOSTAT Click here

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

  6. CHECK HARNESS AND CONNECTOR (COMBINATION METER - LIGHT CONTROL RHEOSTAT)


    1. A017DKME04

      Disconnect the E1 and D3 connectors.

    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      D3-5 (TC) - E1-23 (TC) Always Below 1 Ω
      D3-7 (T) - E1-4 (SW1) Always Below 1 Ω
      D3-5 (TC) - Body ground Always 10 kΩ or higher
      D3-7 (T) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. INSPECT LIGHT CONTROL RHEOSTAT


    1. A017DWQE02

      Remove the light control rheostat with the connector still connected.

    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      D3-5 (TC) - D3-7 (T) Turn the light control rheostat knob fully downwards Below 1 Ω
      D3-5 (TC) - D3-7 (T) Turn the light control rheostat knob fully upwards (Tail cancel ON) 8 kΩ or higher

    NG

    REPLACE LIGHT CONTROL RHEOSTAT Click here

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here