Power Source Mode does not Change to ON (ACC): Procedure

2012 Toyota Prius ThreeSECTION Procedure
WARNING: This page is about a different variant/trim than selected.
  1. CHECK HARNESS OR CONNECTOR (AUXILIARY BATTERY - POWER MANAGEMENT CONTROL ECU) See step   1 

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - POWER MANAGEMENT CONTROL ECU) 

    OK: Go to next step 

  2. CHECK HARNESS OR CONNECTOR (POWER MANAGEMENT CONTROL ECU - BODY GROUND) See step   2 

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER MANAGEMENT CONTROL ECU - BODY GROUND) 

    OK: Go to next step 

  3. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY See step   3 

    NG → See step   7 

    OK: Go to next step 

  4. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - INSTRUMENT PANEL J/B) See step   4 

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  5. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - BODY GROUND) See step   5 

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - BODY GROUND) 

    OK: Go to next step 

  6. INSPECT POWER MANAGEMENT CONTROL ECU See step   6 

    NG → See step   8 

    OK → See step   9 

  7. REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL 
  8. REPLACE POWER MANAGEMENT CONTROL ECU. Refer to  REMOVAL 
  9. USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING 
RENDER: 1.0x

NO RELATED

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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.