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Home >> Kia >> 2020 >> K900 >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Idle Stop & Go (ISG) System >> Schematic Diagrams >> Operating Condition For The ISG Function
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Operating Condition For The ISG Function

  1. Auto stop or Auto start condition 

    If all of the below conditions are satisfied

    Component State Remark
    ISG OFF Switch OFF ISG OFF switch indicator lamp ->OFF
    Engine Coolant Temperature Over 30°C (86°F)  
    Brake vacuum Below -35 kPa  
    Drive door, Seat belt, Hood Closed  
    EMS state
    (TPS/CKP/CMP/WTS/Vehicle speed signal)
    Satisfied DPF Regeneration prohibited
    A/C System Satisfied  
    Battery sensor
    [SOC: Over 78% Temperatuere:2-55°C (35.6 - 131°F)]
    Satisfied  
    ISG related part error Does not occur  
    Vehicle speed Entry the below 0kph after Over 8kph Prohibition the ISG System before 8kph
    Accelerator pedal OFF Engine auto stop condition
    Brake switch ON Engine auto stop condition
    OFF Engine auto stop condition
    Gear state N (Neutal)/D Engine auto stop condition
    R/1/2 Engine auto stop condition
    NOTE: In congested areas, if the driver wishes to stop the vehicle and change lever from D→N, the ignition will turn OFF.
  2. Restriction conditions for Auto stop or Auto start 

    If one of the following conditions is met, the ISG system will not operate properly.

    Component Conditions Remark
    ISG OFF swtich ON ISG OFF switch indicator state
    EMS State
    (TPS/CKP/CMP/WTS/Vehicle speed signal etc.)
    Dissatisfied DPF Regeneration prohibited
    Driver side door, seat belt, hood state Open  
    Brake vacuum Over -35 kPa  
    A/C State Dissatisfied  
    Battery sensor
    (SOC: Over 78%, Temperature: 2 - 60°C))
    Dissatisfied  
    ISG system error Occurred  
    Steering wheel Greater the angle  
    A/C System A/C switch ON, FATC over 6, MTC over 3  
    Defrost Defrost switch ON  
    etc. Downhill, steep uphill  
    Operate the SPAS  
  3. Conditions for forced restart (If none of the below condition is not satisfied) 
    Component Conditions Remark
    Safety requirements Low pressure for braking system Over -35 kPa
    Low battery voltage Maintain excessive electrical load for 3 minutes
    Active defroster of front glass  
    Inertial speed over 1.5 km/h (on downhill)  
    Door open or driver side seat belt unfastened Brake Pedal Pressed
    Ignition switched ON with hood open  
    Engine stopped for long After 300 seconds
    Vehicle parted on a steep slope  
    Convenience requirements A/C ON, FATC over 6, MTC over 3 or HVAC performance dissatisfied  
    ISG OFF' button pressed  
  4. Restriction conditions for Auto-Stop operation 
    Conditions State Remark
    Driver side door, seat belt, hood state (Brake OFF state) Open Start by using "ignition switch" or "button start key" (only)
    CAN error (TCU, FATC/Cluster) Occurred
    EMS state (TPS/CKP/CMP/WTS/Vehicle speed signal) Dissatisfied
    NOTE: In case of error during idle stop, the engine can only be started by using the key.
    CAUTION: The ISG system is strongly networked with the power management. In the event of battery replacement, disconnection of the battery terminal or after changing the engine management system, the reference data regarding the battery charge state and battery condition can be lost. Battery sensor can be reactivated by parking for approximately 4 hours after connecting the negative (-) battery terminal to the battery.
    CAUTION: ISG system deactivation by fault.
    • Fault in communication line (LIN/CAN)

      Fault Electric oil pump

      Fault ESP System

      Fault Limp home mode

    • Fault brake booster vacuum pressure sensor

      Fault Brake master cylinder pressure sensor

      Fault Brake pedal switch

      Fault Battery sensor


    When the ISG related sensors or system error occurs, the ISG OFF switch lights up. Especially when the battery sensor is replaced or reinstalled, the vehicle must be placed in the ignition switch OFF for about 4 hours for recalibration.
    The ISG function should operate properly in approximately 4 hours. However, for the first 25 times, the ISG function will operate regardless of recalibration.
    WARNING: When the engine is in idle stop mode, it can be restarted without the driver taking any action.
    Before leaving the car or doing anything in the engine room area, stop the engine by turning the ignition key to the LOCK position or removing it.