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Diagnosis System

  1. DESCRIPTION 
    1. The hybrid vehicle control ECU has a self-diagnosis system. If the computer, hybrid vehicle control system, or a component is not working properly, the ECU records the conditions that relate to the fault. The ECU also illuminates the master warning light in the combination meter and other appropriate indicators on the multi-information display, such as the HV system warning indicator, the HV battery warning indicator, or the discharge warning indicator.
      Fig 1: Identifying HV System Warning Indicator
      G05304819Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      HINT:

      The master warning light will illuminate when the THS II fails and the light will blink when in inspection mode.

      • When troubleshooting OBD II vehicles, it is necessary to connect an OBD II scan tool that complies with SAE J1978 or connect an intelligent tester to the vehicle. Using one of these testers, it will be possible to read various data output from the vehicle's ECUs.
      • OBD II regulations require that the vehicle's on-board computer illuminates the Malfunction Indicator lamp (MIL) in the instrument panel when the computer detects a malfunction in (1) the emission control systems/ components, (2) the powertrain control components (which affect vehicle emissions), (3) the ECM and hybrid vehicle control ECU. In addition, applicable Diagnostic Trouble Codes (DTCs) prescribed by SAE J2012 are recorded in the hybrid vehicle control ECU memory (See DIAGNOSTIC TROUBLE CODE CHART  ).

      If a malfunction does not recur in 3 consecutive trips, the MIL will go off automatically. However, the DTCs will remain recorded in the hybrid vehicle control ECU memory.

      • To check for DTCs, connect the intelligent tester to the Data Link Connector 3 (DLC3) with the CAN vehicle interface module (CAN VIM). The intelligent tester also allows erasing of DTCs, viewing of freeze frame data, and viewing of various forms of THS II data (for operating instructions, refer to the tester's instruction manual). The DTCs include SAE controlled codes and manufacturer controlled codes. SAE controlled codes must be set as prescribed by the SAE, while manufacturer controlled codes can be set by the manufacturer within prescribed limits (See DIAGNOSTIC TROUBLE CODE CHART  ).
  2. CHECK DLC3 
    1. The hybrid vehicle control ECU uses the ISO 9141-2 communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 9141-2 format.
      Fig 2: Connecting Intelligent Tester To Data Link Connector 3 (DLC3)
      G05285048Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Fig 3: Identifying DLC3 Connector Terminals
      G05009409Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TERMINALS DESCRIPTION

      Symbol Terminal No. Name Reference Terminal Result Condition
      SIL 7 Bus "+" line 5 - Signal ground Pulse generation Always
      CG 4 Chassis ground Body ground 1 Ω or less Always
      SG 5 Signal ground Body ground 1 Ω or less Always
      BATT 16 Battery positive Body ground 11 to 14 V Power switch off
      CANH 6 HIGH-level CAN bus line 14-LOW-level CAN bus line 54 to 69 Ω Power switch off
      CANH 6 HIGH-level CAN bus line 14 - Battery positive 1 MΩ or higher Power switch off
      CANH 6 HIGH-level CAN bus line 4 - Chassis ground 1 kΩ or higher Power switch off
      CANL 14 LOW-level CAN bus line 16- Battery positive 1 MΩ or higher Power switch off
      CANL 14 LOW-level CAN bus line 4 - Chassis ground 1 kΩ or higher Power switch off

      HINT:

      Connect the cable of the intelligent tester to the DLC3, turn the power switch on (IG), and attempt to use the tester. If the display on the tester indicates that a communication error has occurred, there is a problem either with the vehicle or with the tester.

      • If the tester is able to communicate when it is connected to another vehicle, inspect the DLC3 connector of the original vehicle.
      • If communication is still not possible when the tester is connected to another vehicle, the problem may be in the tester itself. Consult the tester's instruction manual for information on service or repair of the tester.
  3. INSPECT AUXILIARY BATTERY 
    1. Measure the voltage of the auxiliary battery.

      Standard Voltage: 10 to 14 V 

    2. Inspect the auxiliary battery, fuses, fusible links, wiring harness, connectors and ground.
  4. CHECK MIL 
    1. The MIL will illuminate when the power switch is turned on (IG), before the "READY" light comes on. If the MIL does not illuminate, troubleshoot the MIL circuit (See MIL CIRCUIT ).
    2. When the "READY" light turns on, the MIL should turn off. If the MIL remains on, the diagnosis system has detected a malfunction or abnormality in the system.
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