2012 Toyota Prius ThreeFACTORY OEM SERVICE PROCEDURE

Terminals Of Ecu

  1. CHECK SEAT BELT CONTROL ECU 
    Fig 1: Seat Belt Control ECU Connector Terminal Identification
    GTY223823Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the seat belt control ECU connectors.
    2. Measure the resistance and voltage according to the value(s) in the table below.
      Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition
      L2-7 (+B) - Body ground B - Body ground Battery voltage Always 11 to 14 V
      L2-8 (PGND) - Body ground W-B - Body ground Body ground Always Below 1 Ω
      L3-8 (IG1) - Body ground R - Body ground Seat belt control ECU power supply Power switch on (IG) 11 to 14 V
      Power switch off Below 1 V

      If the result is not as specified, there may be a malfunction on the wire harness side.

    3. Reconnect the connectors.
    4. Measure the voltage according to the value(s) in the table below.
      Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition
      L2-2 (MOR+) - L2-1 (MOR-) B - W Seat belt motor RH power supply Power switch on (IG) 4.0 to 8.5 V
      Power switch off Below 1 V
      L2-3 (MOL+) - L2-4 (MOL-) B - W Seat belt motor LH power supply Power switch on (IG) 4.0 to 8.5 V
      Power switch off Below 1 V

      If the result is not as specified, the ECU may be malfunctioning.

  2. CHECK DRIVING SUPPORT ECU 
    Fig 2: Driving Support ECU Connector Terminal Identification
    GTY213489Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the driving support ECU connector.
    2. Measure the voltage and resistance according to the value(s) in the table below.
      Terminal No. (Symbol) Wiring Color Terminal Description Condition Specified Condition
      L60-30 (B) - Body ground B - Body ground Power supply Power switch on (IG) 11 to 14 V
      Power switch off Below 1 V
      L60-25 (GND) - Body ground W-B - Body ground Body ground Always Below 1 Ω
      L60-27 (STP-) - Body ground Y - Body ground Stop light switch signal input Brake pedal depressed 7.5 to 14 V
      L60-27 (STP-) - Body ground Y - Body ground Stop light switch signal input Brake pedal released Below 1 V
      L60-28 (ST1-) - Body ground R - Body ground Stop light switch signal input Power switch on (IG),
      Brake pedal released      		 7.5 to 14 V
      L60-28 (ST1-) - Body ground R - Body ground Stop light switch signal input Power switch on (IG),
      Brake pedal depressed      		 Below 1 V
      L60-5 (PBSW) - Body ground L - Body ground Pre-collision brake cancel switch Pre-collision brake cancel switch on Below 1 Ω
      Pre-collision brake cancel switch off 10 kΩ or higher
    3. Measure the voltage and resistance according to the value(s) in the table below.

      If the result is not as specified, there may be a malfunction on the wire harness side.

    4. Reconnect the connector.
    5. Measure the voltage according to the value(s) in the table below.
      Terminal No. (Symbols) Wiring Color Terminal Description Condition Specified Condition
      L60-17 (CA2L) - L60-25 (GND) W - W-B CAN communication signal Power switch on (IG) Pulse generation
      (See waveform 1)
      L60-18 (CA1N) - L60-25 (GND) L - W-B CAN communication signal Power switch on (IG) Pulse generation
      (See waveform 2)
      L60-23 (CCS) - L60-25 (GND) V - W-B Cruise control main switch signal Power switch on (IG) 10 to 14 V
      L60-23 (CCS) - L60-25 (GND) V - W-B Cruise control main switch signal Power switch on (IG),
      CANCEL switch on      		 6.6 to 10.1 V
      L60-23 (CCS) - L60-25 (GND) V - W-B Cruise control main switch signal Power switch on (IG),
      Main switch on      		 Below 1 V
      L60-39 (CA2H) - L60-25 (GND) B - W-B CAN communication signal Power switch on (IG) Pulse generation
      (See waveform 3)
      L60-40 (CA1P) - L60-25 (GND) Y - W-B CAN communication signal Power switch on (IG) Pulse generation
      (See waveform 4)
    6. WAVEFORM 1
      Fig 3: Identifying Waveform 1
      GTY234033Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. CAN communication signal
        Driving support ECU Terminal Name Between CA2L and GND
        Tester Range 1 V/DIV., 10 μsec./DIV.
        Condition Power switch on (IG)

        HINT: 

        The waveform varies depending on the CAN communication signal.

    7. WAVEFORM 2
      Fig 4: Identifying Waveform 2
      GTY237012Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. CAN communication signal
        Driving support ECU Terminal Name Between CA1N and GND
        Tester Range 1 V/DIV., 10 μsec./DIV.
        Condition Power switch on (IG)
    8. WAVEFORM 3
      Fig 5: Identifying Waveform 3
      GTY237012Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. CAN communication signal
        Driving support ECU Terminal Name Between CA2H and GND
        Tester Range 1 V/DIV., 10 μsec./DIV.
        Condition Power switch on (IG)

        HINT: 

        The waveform varies depending on the CAN communication signal.

    9. WAVEFORM 4
      Fig 6: Identifying Waveform 4
      GTY234033Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. CAN communication signal
        Driving support ECU Terminal Name Between CA1P and GND
        Tester Range 1 V/DIV., 10 μsec./DIV.
        Condition Power switch on (IG)
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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.

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