LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2012 >> Prius Plug-in >> Repair and Diagnosis >> Restraints >> Restraints Control Systems >> Pre-Collision System (Plug-In) (Diagnostic Codes & Circuit Tests) >> Pre-Collision System >> Circuit Tests >> Power Source Circuit >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Power Source Circuit: Procedure

  1. CHECK HARNESS AND CONNECTOR (GND CIRCUIT) 
    1. Disconnect the seat belt control ECU connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L133-8 (PGND) - Body ground Always Below 1 Ω
    3. Reconnect the seat belt control ECU connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT) 

    OK: Go to next step 

  2. CHECK HARNESS AND CONNECTOR (IG1 CIRCUIT) 
    1. Disconnect the seat belt control ECU connector.
    2. Turn the power switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      L134-8 (IG1) - L133-8 (PGND) Power switch on (IG) 11 to 14 V
    4. Reconnect the seat belt control ECU connector.

    NG → See step   4 

    OK: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (+B CIRCUIT) 
    1. Disconnect the seat belt control ECU connector.
      Fig 1: Checking L133 Connector Terminals
      GTY330870Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      L133-7 (+B) - Body ground Always 11 to 14 V
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Seat Belt Control ECU)
    3. Reconnect the seat belt control ECU connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (+B CIRCUIT) 

    OK → See step   8 

  4. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY 
    1. Remove the instrument panel junction block assembly.
      Fig 2: Identifying Instrument Panel Junction Block Assembly Connector Terminals
      GTY334400Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *a Instrument Panel Junction Block Assembly - -
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      2E-1 - 2B-16 Always 10 kΩ or higher
      2E-1 - 2B-16 When auxiliary battery voltage applied to terminals 2B-25 and 2B-6 Below 1 Ω
    3. Reinstall the instrument panel junction block assembly.

    NG → See step   9 

    OK: Go to next step 

  5. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK - SEAT BELT CONTROL ECU) 
    1. Disconnect the instrument panel junction block assembly connector.
    2. Disconnect the seat belt control ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      2B-16 - L134-8 (IG1) Always Below 1 Ω
      2B-16 - Body ground Always 10 kΩ or higher
      L134-8 (IG1) - Body ground Always 10 kΩ or higher
    4. Reconnect the seat belt control ECU connector.
    5. Reconnect the instrument panel junction block assembly connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK - SEAT BELT CONTROL ECU) 

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK - BODY GROUND) 
    1. Disconnect the instrument panel junction block assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      2B-6 - Body ground Always Below 1 Ω
    3. Reconnect the instrument panel junction block assembly connector.

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

    OK: Go to next step 

  7. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK - POWER MANAGEMENT ECU) 
    1. Disconnect the instrument panel junction block assembly connector.
    2. Disconnect the power management control ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      2B-25 - L136-2 (IG1D) Always Below 1 Ω
      2B-25 - Body ground Always 10 kΩ or higher
      L136-2 (IG1D) - Body ground Always 10 kΩ or higher
    4. Reconnect the power management control ECU connector.
    5. Reconnect the instrument panel junction block assembly connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK - POWER MANAGEMENT ECU) 

    OK → REPAIR OR REPLACE HARNESS OR CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK - AUXILIARY BATTERY) 

  8. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE 
  9. REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL