2012 Toyota Avalon BaseFACTORY OEM SERVICE PROCEDURE

Engine Switch Indicator Circuit: Procedure

  1. INSPECT ENGINE SWITCH 
    1. Disconnect the D21 switch connector.
      Fig 1: Identifying D21 Switch Connector Terminals
      GTY170228Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Connect the positive (+) lead to terminal "A" and the negative (-) lead to terminal "B" of the engine switch.
    3. Check if the illumination for the engine switch comes on.

      OK

      Positive (+) Connection (Symbols) Negative (-) Connection (Symbols) Illumination Condition
      D21-11 (SWIL) D21-4 (COM) or D21-5 (GND) Comes on
      D21-12 (INDS) D21-4 (COM) or D21-5 (GND) Comes on
      D21-13 (INDW) D21-4 (COM) or D21-5 (GND) Comes on

    NG → REPLACE ENGINE SWITCH 

    OK: Go to next step 

  2. CHECK WIRE HARNESS (ENGINE SWITCH - POWER SOURCE CONTROL ECU AND BODY GROUND) 
    1. Disconnect the D44 ECU connector.
      Fig 2: View Of Disconnected D44 ECU Connector Terminals
      GTY167194Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.
      Fig 3: Identifying D21 Switch Connector Terminals
      GTY177626Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Resistance

      Tester Connection (Symbols) Condition Specified condition
      D44-4 (INDS) - D21-12 (INDS) Always Below 1 Ω
      D44-13 (INDW) - D21-13 (INDW) Always Below 1 Ω
      D44-36 (SWIL) - D21-11 (SWIL) Always Below 1 Ω
      D44-4 (INDS) - Body ground Always 1 MΩ or Higher
      D44-13 (INDW) - Body ground Always 1 MΩ or Higher
      D44-36 (SWIL) - Body ground Always 1 MΩ or Higher

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → REPLACE POWER SOURCE CONTROL ECU 

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.