LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2005 >> Prius >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (SFI) - Diagnostics >> Precaution
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Engine Control System (SFI) - Diagnostics: Precaution

  1. PRECAUTIONS FOR HIGH-VOLTAGE CIRCUIT INSPECTION AND SERVICE 
    1. Technicians to be engaged in inspection and service on high-voltage components and systems should receive special training.
    2. All the high-voltage wire harness connectors are colored orange: the HV battery and other high-voltage components are identified by the "High Voltage" caution labels. Do not touch these connectors and components before removing the service plug. Remove the service plug prior to touching these connectors and components.
    3. Before inspecting or servicing the high-voltage components/systems, be sure to take safety precautions such as wearing insulated gloves and removing the service plug to prevent electric shock or electrocution. Store the removed service plug in your pocket to prevent other technicians from reinstalling it while you are servicing high-voltage components/systems.
    4. After removing the service plug, wait at least for 5 minutes before touching any of the high-voltage connectors and terminals.

      HINT:

      At least 5 minutes is required to discharge electricity from the high-voltage condenser inside the inverter.

      Fig 1: Precautions For Removing Service Plug And Connectors
      G02619821Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    5. Before wearing insulated gloves, make sure that they are not ruptured, torn or damaged in any other way. Do not wear wet insulated gloves.
    6. When servicing, be careful not to drop metallic materials like a mechanical pencil or tools etc. Causing a short circuit may result.
    7. Wear the insulated gloves before touching a bare high-voltage terminal. Verify that electricity has discharged from the terminal (approximately 0 V) using an electrical tester.
      Fig 2: Precautions For Wearing Insulated Gloves
      G02619822Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    8. After disconnecting or exposing a high-voltage connector or terminal, insulate it immediately using insulation tape.
    9. The screw of a high-voltage terminal should be tightened firmly to the specified torque. Either insufficient or excessive tightening torque can cause HV system failure.
    10. Call other technicians' attention to prevent accidents during working on the high-voltage components/systems by posting a sigh to notify them (see REPAIR INSTRUCTION ).
    11. Prior to reinstalling the service plug, again, verify whether or not any parts or tools have been left behind, and check if high-voltage terminal screws have been securely tightened as well as the connectors have been properly reconnected.
      Fig 3: Precautions For Disconnecting Or Exposing High-Voltage Connector Or Terminal
      G02619823Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. PRECAUTIONS TO BE OBSERVED WHEN INSPECTING OR SERVICING ENGINE COMPARTMENT 

    The PRIUS automatically turns the engine ON and OFF when the power switch is ON (READY lamp on the instrument panel is being illuminated). Turn the HV main system OFF before servicing inside the engine compartment.

    Fig 4: Precautions For Servicing Inside Engine Compartment
    G02619824Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. INSPECTION MODE 

    HINT:

    When the A/C compressor operation is not required, the engine is warmed up, and the battery is charged properly, the PRIUS automatically stops the engine while the vehicle is at rest. In the case of a continuous engine operation is needed for performing engine maintenance, activate inspection mode. Inspection mode enables the engine to run continuously.

    Activating inspection mode (not using the hand-held tester) Perform the following steps from (1) through (4) in 60 seconds.

    1. Turn the power switch ON (IG).
    2. Fully depress the accelerator pedal twice with the transmission in the P position.
    3. Fully depress the accelerator pedal twice with the transmission in the N position.
    4. Fully depress the accelerator pedal twice with the transmission in the P position.
    5. Check that the HV system warning lamp flashes on the multi-information display.
    6. Start the engine by pushing the power switch, depressing the brake pedal.
      Fig 5: Inspecting HV System Warning Lamp Flashes On Multi-Information Display
      G02619825Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    Activating inspection mode (Using the hand-held tester)

    1. Connect the hand-held tester to the DLC3.
    2. Turn the power switch ON (IG).
    3. Turn the hand-held tester ON.
    4. Select the following menu items: DIAGNOSIS / OBD/MOBD / HV ECU / ACTIVE TEST / INSPECTION MODE / ON.
    5. Check that the HV system warning flashes on the multi-information display and the master warning lamp is illuminated in the combination meter.
    6. Start the engine by pushing the power switch, depressing the brake pedal.
      Fig 6: Checking HV System Warning Flashes On MULTI-Information Display
      G02619826Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    Deactivating inspection mode

    1. Turn the power switch OFF. The HV main system turns off simultaneously.
    NOTE:
    • The idling speed in inspection mode is approximately 1,000 RPM. The engine speed increases to 1,500 RPM if the accelerator pedal is depressed by less than 60%. If the accelerator pedal is depressed by more than 60%, the engine speed increases to 2,500 RPM. 
    • If a DTC is set during inspection mode, the master warning lamp and the error warning lamp illuminate on the multi-information display. 
    • When the master warning lamp illuminates during inspection mode, deactivate inspection mode, and check a DTC(s). 
    • Driving the vehicle without deactivating inspection mode may damage the transaxle. 
  4. FOR USING OBD II SCAN TOOL OR HAND-HELD TESTER 
    CAUTION: Observe the following items for safety reasons:  
    • Read its instruction books before using the scan tool or the tester. 
    • Prevent the tester cable from being caught on the pedals, shift lever and steering wheel when driving with the tester connected to the vehicle. 
    • When driving the vehicle for testing purposes using the scan tool or the tester, two persons are required. One is for driving the vehicle, and the other operates the tester. 
  5. INITIALIZATION 
    NOTE: When disconnecting the negative (-) battery cable, initialize the following systems after the terminal is reconnected. 
    POWER WINDOW CONTROL SYSTEM DESCRIPTION

    System Name See page
    Power Window Control System INITIALIZATION

    HINT:

    Initialization can not be completed by only removing the battery.

  6. NOTICES FOR HYBRID SYSTEM ACTIVATION 
    • When the warning lamp is illuminated or the battery has been disconnected and reconnected, pressing the power switch may not start the system on the first try. If so, press the power switch again. 
    • With the power switch's power mode changed to ON (IG), disconnect the battery. If the key is not in the key slot during reconnection, DTC B2799 may be output. 
scientia non olet · About LEMON Manuals