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Home >> Toyota >> 2012 >> Prius Two >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Meter / Gauge System (Except Plug-In) (Diagnostic Codes & Symptom Tests) >> Meter / Gauge System >> Symptom Tests >> Meter Illumination does not Dim at Night >> Procedure

Meter Illumination does not Dim at Night: Procedure

  1. CHECK CAN COMMUNICATION SYSTEM 
    1. Check if a CAN communication DTC is output. Refer to DIAGNOSIS SYSTEM .

      Result

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

    B → See step   6 

    A: Go to next step 

  2. CHECK DTC (LIGHT CONTROL SENSOR CIRCUIT) 
    1. Check if DTC B1244 is output. Refer to DTC CHECK / CLEAR .

      Result

      Result Proceed to
      B1244 is not output. A
      B1244 is output. B

    B → See step   7 

    A: Go to next step 

  3. CHECK OPERATION (HEATER CONTROL PANEL) 
    1. Turn the power switch on (IG).
    2. Turn the light control switch to the tail, head, or AUTO position.
    3. Cover the light control switch.
    4. Check the heater control panel illumination.

      Result

      Result Proceed to
      Heater control panel illumination does not operate normally. A
      Heater control panel illumination operates normally. B

      HINT: 

      Both the heater control panel and combination meter assembly illumination dim according to the dimmer signal. Therefore, when only the meter illumination does not dim at night, replace the combination meter assembly.

    B → See step   8 

    A: Go to next step 

  4. CHECK OPERATION (AUTOMATIC LIGHT CONTROL SYSTEM) 
    1. Turn the power switch on (IG).
    2. Turn the light control switch to the AUTO position.
    3. Cover the automatic light control sensor.
    4. Check the taillights and low beam headlights.

      OK

      The taillights and low beam headlights come on.

    5. Uncover the automatic light control sensor.
    6. Check the low beam headlights and taillights.

      OK

      The low beam headlights and taillights go off.

      Result

      Result Proceed to
      Automatic light control system operates normally. A
      Automatic light control system does not operate normally. B

    B → See step   9 

    A: Go to next step 

  5. REPLACE MAIN BODY ECU 
    1. Replace the main body ECU with a new or a known good one. Refer to REMOVAL .

      OK

      The operation of the combination meter assembly returns to normal.

      HINT: 

      The meter ECU (meter circuit plate No. 3) controls the meter illumination based on an auto dimmer signal from the main 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 does not send an auto dimmer signal. The second is that the meter ECU (meter circuit plate No. 3) does not dim the meter illumination even though the meter ECU (meter circuit plate No. 3) receives an auto dimmer signal.

    NG → See step   8 

    OK → END 

  6. GO TO CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING 
  7. GO TO LIGHTING SYSTEM. Refer to  DTC B1244: Light Sensor Circuit Malfunction 
  8. REPLACE COMBINATION METER ASSEMBLY (NO. 3 METER CIRCUIT PLATE). Refer to  DISASSEMBLY 
  9. CHECK LIGHTING SETTING. Refer to  CUSTOMIZE PARAMETERS