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Home >> Hyundai >> 2021 >> Ioniq Hybrid SEL >> Repair and Diagnosis >> Hybrid/Electric Powertrain >> Testing and Diagnosis >> HCU/Low Dc-Dc Converter Diagnosis (HEV) >> DTC P1790: Variant Coding Error >> System Inspection

System Inspection

  1. Remove the undercover below the vehicle and check the connector of the engine clutch actuator (HCA) for normal connection and corrosion.
    • If the connector is connected incorrectly, connect the connector correctly and check the system.
    • Check the connector terminal on the HCA for corrosion.
    • If there is a leak from the engine clutch system, replace the part where the leak is occurring.
    • If the connector is connected correctly and there is no corrosion, carry out No. 2 item.
  2. Erase DTC, request for engine clutch/motor resolver learning using the GDS, and check if the same DTC occurs.
    • If the same DTC occurs, carry out No. 3 item.
    • If the same DTC does not occur, check if a different DTC has occurred.
    • If the engine clutch/motor resolver learning function has failed, carry out measures according to the reason for failure.
  3. When 5 seconds have passed after turning the ignition switch off, only turn the ignition switch on (Not READY) and check the following items in the sensor data diagnosis.
    • If the operation position of the engine clutch actuator is -4.0 mm or higher, replace the HCA.
    • If the operation position of the engine clutch actuator is near -4.5 mm but the operation pressure of the engine clutch actuator is 1.4 bar or higher, replace the HCA.
  4. After replacing it, it is necessary to carry out (1) Initialization of the engine clutch initialization line learning and diagnosis information → (2) Removal of air from engine clutch hydraulic pressure line →(3) Engine clutch/Motor Resolver Adaptation in order using the GDS.

    * In case the SOC is below 35%, when the shift gear is left at P in the ignition switch "ON"/HEV Ready status, the engine will operate and the SOC will be charged.

    * When carrying out air bleeding from the hydraulic line of the engine clutch after replacing the engine clutch system, the function will be carried out normally only when the temperature of the hydraulic oil (brake oil DOT 3) is at room temperature (over 20°C).

NOTE:
  • Method to confirm the reasons and respond when the optional function of the engine clutch fails
    • If the optional function of the engine clutch fails, check HCU Error Code and LuK Error Code on the screen of the diagnostic tool and carry out inspection items.
  1. HCU Error Code 
    Information Code Inspection Procedure
    1 1. Re-perform the "Vehicle S/W Management" after confirm the gear position "P".
    2 1. Re-perform the "Vehicle S/W Management" after confirm the acceleration pedal release.
    3 1. Check the DTC of the BMS system, and if there is a DTC, repair the DTC first.
    2. Operate the engine for 2 minutes when the charge is insufficient after confirming the charge of the main battery.
    3. Re-perform the "Vehicle S/W Management".
    4 1. Check the DTC of the BMS system, and if there is a DTC, repair the DTC first.
    2. Operate the engine for 2 minutes when the charge is insufficient after confirming the charge of the main battery.
    3. Re-perform the "Vehicle S/W Management".
    5 1. Check the DTC of the MCU system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
    6 1. Check the DTC of the MCU system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
    7 1. Check the DTC of the BMS system, and if there is a DTC, repair the DTC first.
    2. Operate the engine for 2 minutes when the charge is insufficient after confirming the charge of the main battery.
    3. Re-perform the "Vehicle S/W Management".
    8 1. Operate the engine for 2 minutes to raise the temperature of the vehicle.
    2. Re-perform the "Vehicle S/W Management".
    9 1. Check the DTC of all system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
    10 (Filling Check) 1. If the engine is running, wait until the engine stops.
    2. Re-perform the "Vehicle S/W Management" after confirm the engine "OFF".
    10 (Refill) 1. If the engine is running, wait until the engine stops.
    2. Re-perform the "Vehicle S/W Management" after confirm the engine "OFF".
    10 (Touch Point) 1. Re-perform the "Vehicle S/W Management" after ignition "OFF/ON"
    20 (Filling Check) 1. Check the DTC of the MCU system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/WManagement".
    20 (Touch Point) 1. Re-perform the "Vehicle S/W Management" after ignition "OFF/ON"
    30 (Filling Check) 1. Check the DTC of all system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
    30 (Touch Point) 1. If the engine is running, wait until the engine stops.
    2. Re-perform the "Vehicle S/W Management" after confirm the engine "OFF".
    40 (Touch Point) 1. Check the DTC related to the engine clutch, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
    50 (Touch Point) 1. Check the DTC of the MCU system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
    60 (Touch Point) 1. Check the DTC of the MCU system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
  2. LuK Error Code 
    Code Cause Cause
    A4 Faulty HCA pressure sensor 1. Check the DTC related to the engine clutch, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/WManagement".
    D1 HCA block stuck 1. Check the DTC related to the engine clutch, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/WManagement".
    C6 Engine clutch open time over 1. Check the DTC related to the engine clutch, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/WManagement".
    E9 Engine clutch coupling time over 1. Check the DTC related to the engine clutch, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/WManagement".
    96 Motor speed is over 10 RPM during filling check and refill 1. Shift the gear position to "P".
    2. Check the motor speed. (below 10 RPM)
    3. Confirm that the accelerator pedal has been operated while performing "Vehicle S/WManagement"
    4. Re-perform the "Vehicle S/WManagement".
    F0 Engine clutch position information unreliable 1. Check the DTC related to the engine clutch, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/WManagement".
    D3 Drive motor torque error 1. Check the DTC of the MCU system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/WManagement".
    77 Drive motor is not operated 1. Check the DTC of the MCU system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/WManagement".
    EA Engine clutch not open 1. Check the DTC related to the engine clutch, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/WManagement".
    D9 TP learning value range exceeded 1. Check the DTC related to the engine clutch/MCU system, and if there is a DTC, repair the DTC first.
    2. Check the assembly of the engine clutch system.
    3. Re-perform the "Vehicle S/WManagement".
    D2 Learning time exceeded 1. Check the DTC related to the engine clutch, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
    F5 Failure to learn due to engine failure 1. Check the DTC of the EMS system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
    F6 Failure to learn due to engine operation 1. Confirm that the accelerator pedal has been operated while performing "Vehicle S/W management"
    2. Check the DTC of the EMS system, and if there is a DTC, repair the DTC first.
    3. Re-perform the "Vehicle S/W Management".
    DB Drive motor speed error 1. Check the DTC of the MCU system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
    72 Engine clutch slip speed is low 1. Confirm that the accelerator pedal has been operated while performing "Vehicle S/W management"
    2. Check the DTC of the HCU/MCU/EMS system, and if there is a DTC, repair the DTC first.
    3. Re-perform the "Vehicle S/W Management".
    6F Engine clutch slip speed is high 1. Check the DTC related to the engine clutch, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
    75 Drive motor operates in the opposite direction 1. Check the DTC of the MCU system, and if there is a DTC, repair the DTC first.
    2. Re-perform the "Vehicle S/W Management".
    6E Engine clutch over temperature 1. Waits for 2 minutes for the temperature drop of the engine clutch.
    2. Re-perform the "Vehicle S/W Management".
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