СИСТЕМА ECD СИСТЕМА ДИАГНОСТИКИ


  1. DESCRIPTION


    1. A01BG58E02

      Description for M-OBD


      • When troubleshooting Multiplex OBD (M-OBD) vehicles, the only difference from the usual troubleshooting procedure is to connect the intelligent tester to the vehicle and read off various data output from the vehicle's ECM.

      • The vehicle's on-board computer indicates the Malfunction Indicator Lamp (MIL) on the instrument panel when the computer detects a malfunction in the computer itself or in drive system components. In addition to an indication of the MIL when a malfunction is detected, the applicable Diagnostic Trouble Codes (DTCs) are recorded in the ECM memory Click here. When the malfunction does not reoccur, the MIL is indicated until the ignition switch is turned off, and then the MIL is not indicated when the ignition switch is turned on but the DTCs remain recorded in the ECM memory.

      • A01BHY4E01

        To check the DTC, connect the intelligent tester to the Data Link Connector 3 (DLC3) on the vehicle or read the number of blinks of the check engine warning light when the TC and CG terminals on the DLC3 are connected. The intelligent tester also enables you to erase the diagnostic trouble codes and activate the several actuators and check the freeze frame data and various forms of engine data (for operating instructions, see the intelligent tester instruction book).

  2. NORMAL MODE AND CHECK MODE

    The diagnosis system operates in the normal mode during normal vehicle use. It also has a check (test) mode for technicians to simulate malfunction symptoms and troubleshoot. Most DTCs use 2-trip detection logic to prevent an erroneous detection, and ensure a thorough malfunction detection. By switching the ECM to the check (test) mode using the intelligent tester when troubleshooting, a technician can cause the MIL to light up for a malfunction that is only detected once or momentarily (intelligent tester only) (See step 3).

  3. 2-TRIP DETECTION LOGIC

    When a logic malfunction is first detected, the malfunction is temporally stored in the ECM memory (1st trip). If the same malfunction is detected again during the second drive test, this second detection causes the MIL to light up (2nd trip) (however, the ignition switch must be turned off between the 1st trip and 2nd trip).

  4. FREEZE FRAME DATA

    The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

  5. DLC3 (Data Link Connector 3)

    A01BC3RE25

    The vehicle's ECM uses the ISO 14230 (M-OBD) communication protocol. The terminal arrangement of DLC3 complies with ISO 15031-03 and matches the ISO 14230 format.

    Symbol Terminal No. Name Reference Terminal Result Condition
    SIL 7 Bus "+" line 5 - Signal ground Pulse generation During transmission
    CG 4 Chassis ground Body ground 1 Ω or less Always
    BAT 16 Battery positive Body ground 9 to 14 V Always

    Tech Tips

    If the display shows a communication error message when the cable of the intelligent tester is connected to the DLC3, the ignition switch is turned to the ON position, and the tester is operated, there is a problem on either the vehicle side or the tester side.


    • If communication is normal when the tester is connected to another vehicle, inspect the DLC3 on the original vehicle.

    • If communication is impossible when the tester is connected to another vehicle, the problem is probably in the tester itself. Consult the Service Department listed in the intelligent tester's operator's manual.

  6. BATTERY VOLTAGE

    If the voltage is below 11 V, recharge the battery before proceeding.

  7. MIL (Malfunction Indicator Lamp)


    1. The MIL illuminates when the ignition switch is on and the engine is not running.

      Tech Tips

      If the MIL is not illuminated, check the MIL circuit (refer to MIL CIRCUIT Click here.

    2. The MIL should turn off when the engine is started. If the MIL remains illuminated, the diagnosis system will detect a malfunction or abnormality in the system.