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

DESCRIPTION

The meter ECU receives signals from this circuit to adjust the illumination of the meter. The meter ECU sets the illumination level based on the user operation of the light control rheostat.

Tech Tips


  • The meter illumination level can be adjusted by operating the light control rheostat.


  • The meter illumination dims when the light control switch is turned to the tail, head, or AUTO position at night.


  • Setting the meter illumination to maximum brightness cancels the above dimming of the meter illumination.

WIRING DIAGRAM

A004VODE14

PROCEDURE


  1. SYSTEM CHECK


    1. Confirm the symptoms.

      Result
      Result Proceed to
      Meter illumination does not change in operating the light control rheostat. A
      Dimmer function cannot be canceled. B

    B

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

    A

  2. READ VALUE USING INTELLIGENT TESTER (RHEOSTAT VALUE)


    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 / 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 (dark), Max.: 255 (bright) The light control rheostat value 0 (dark) The value changes with the rheostat operation
      The light control rheostat value 255 (bright)
      OK
      The value displayed on the intelligent tester gradually changes as the actual rheostat knob operation.

    NG

    INSPECT LIGHT CONTROL RHEOSTAT Click here

    OK

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


    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 / 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/OFF or ON OFF: Tail cancel switch off -
      ON: Tail cancel switch on -

      Tech Tips

      The tail cancel switch is operated by turning the light control rheostat knob fully upward

      OK
      Condition displayed on the intelligent tester is the same as the actual light control rheostat knob position.

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

    INSPECT LIGHT CONTROL RHEOSTAT Click here

  4. INSPECT LIGHT CONTROL RHEOSTAT


    1. A004W8FE05
      Text in Illustration
      *a

      Component without harness connected

      (Light Control Rheostat)

      Remove the light control rheostat Click here.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      1 (E) - 3 (RV) Turn the light control rheostat knob fully downwards (MIN.) Below 50 Ω
      Light control rheostat knob position is between MIN. and MAX. The value changes gradually (Between 0 to 12 kΩ)
      Turn the light control rheostat knob fully upwards (MAX.) 8 to 12 kΩ

    NG

    REPLACE LIGHT CONTROL RHEOSTAT Click here

    OK

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


    1. Disconnect the H19 and H40 connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H19-14 (REV) - H40-3 (RV) Always Below 1 Ω
      H19-14 (REV) - Body ground Always 10 kΩ or higher
      H19-36 (SW3) - H40-1 (E) Always Below 1 Ω
      H19-36 (SW3) - Body ground Always 10 kΩ or higher

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


    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 / 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/OFF or ON OFF: Tail cancel switch off -
      ON: Tail cancel switch on -

      Tech Tips

      The tail cancel switch is operated by turning the light control rheostat knob fully upward

      OK
      Condition displayed on the intelligent tester is the same as the actual light control rheostat knob position.

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

  7. INSPECT LIGHT CONTROL RHEOSTAT


    1. A004W8FE06
      Text in Illustration
      *a

      Component without harness connected

      (Light Control Rheostat)

      Remove the light control rheostat Click here.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      5 (TC) - 7 (T) Light control rheostat position is except below Below 50 Ω
      Turn the light control rheostat knob fully upwards (Tail cancel switch is on) 8 to 12 kΩ

    NG

    REPLACE LIGHT CONTROL RHEOSTAT Click here

    OK

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


    1. Disconnect the H19 and H40 connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H19-16 (SW1) - H40-7 (T) Always Below 1 Ω
      H19-16 (SW1) - Body ground Always 10 kΩ or higher
      H19-15 (TC) - H40-5 (TC) Always Below 1 Ω
      H19-15 (TC) - Body ground Always 10 kΩ or higher

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR