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Home >> Lexus >> 2003 >> GX 470 >> Repair and Diagnosis >> Electrical >> Gauges >> Combination Meter - Diagnosis >> Operating Light Control Rheostat Does Not Change Light Brightness >> Inspection Procedure

Inspection Procedure

  1. CHECK ILLUMINATION 
    1. Operate the rheostat and check that the quantity of light for the combination meter assy, audio system and A/C control panel etc. are normally changed.
    CONDITION

    A Combination meter does not change.
    B All light do not change.
    1. B: GO TO STEP   5 
    2. A: GO TO NEXT STEP 
  2. CHECK DATA LIST 
    1. Check the date list of body ECU.
    1. OK: NORMAL 
    2. NG: GO TO NEXT STEP 
  3. INSPECT LIGHT CONTROL RHEOSTAT 
    1. Check the continuity of light control rheostat when light control rheostat operation as shown in SPECIFIED CONDITION  .

    Standard: 

    SPECIFIED CONDITION

    Terminal (Symbol) Condition Specified condition
    1 (T) <=> Body ground Ignition switch ON, Tail-light switch OFF --> ON Below 1V --> 10 - 14V
    2 (IG) <=> Body ground Ignition switch OFF -->ON Below 1V --> 10 - 14V
    5 (E) <=> Body ground Constant Continuity
    Fig 1: Inspecting Light Control Rheostat
    G03470546Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPLACE LIGHT CONTROL RHEOSTAT 
    2. OK: GO TO NEXT STEP 
  4. CHECK HARNESS AND CONNECTOR 
    1. Check the continuity between terminals 8 (TC) of light control rheostat and B5-18 of combination meter connector.

      Standard: There is continuity. 

    2. Check the continuity between terminals C9-16 of combination meter assy and B5-5 of body ECU.

      Standard: There is continuity. 

    1. OK: REPLACE COMBINATION METER ASSY 
    2. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 
  5. INSPECT LIGHT CONTROL RHEOSTAT 
    1. Check the continuity of light control rheostat when light control rheostat operation as shown in SPECIFIED CONDITION  .

    Standard: 

    SPECIFIED CONDITION

    Terminal (Symbol) Condition Specified condition
    1 (T) <=> Body ground Ignition switch ON, Tail-light switch OFF --> ON Below 1V --> 10 - 14V
    2 (IG) <=> Body ground Ignition switch OFF --> ON Below 1V --> 10 - 14V
    5 (E) <=> Body ground Constant Continuity
    Fig 2: Inspecting Light Control Rheostat
    G03470547Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPLACE LIGHT CONTROL RHEOSTAT 
    2. OK: GO TO NEXT STEP 
  6. CHECK HARNESS AND CONNECTOR (BETWEEN LIGHT CONTROL RHEOSTAT AND INSTRUMENT PANEL JUNCTION) 
    1. Check the continuity between 1 (T) of light control rheostat and R12-21 of instrument panel junction block assy.

      Standard: There is continuity. 

      Fig 3: Checking Continuity Between 1 (T) And R12-21
      G03470548Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 
    2. OK: GO TO NEXT STEP 
  7. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSY 
    1. Measure voltage between terminal R12-21 of instrument panel junction block assy and body ground.

    Standard: 

    SPECIFIED CONDITION

    Combination switch Specified condition
    OFF Below 1 V
    TAIL 10 - 14 V
    1. OK: REPLACE COMBINATION METER ASSY 
    2. NG: REPAIR OR REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSY 
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