Kia Sorento: Description and Operation

Kia Sorento (MQ4, 2021-2026) Service Manual / Engine Control / Fuel System / ISG (Idle Stop & Go) System / Description and Operation

Description

•	ISG system improves fuel efficiency and reduces emissions by temporary stop the vehicle engine either at waiting for a traffic signal or stopping.

•	The ISG system is always ON whevenever the engine start.

•	If the vehicle is completely stopped while the brake pedal is pressed, the engine will automatically stop and the AUTO STOP indicator (green) ON.

•

If you release your foot from the brake pedal while the engine is automatically stopped, the engine will restart and the AUTO STOP indicator will OFF.

During AUTO HOLD operation, the engine remains stopped even if you release the brake pedel. When you press the accelerator pedal, the engine will restart.

System Components

The ISG system consists of a mutual network among the related components. Refer to relevant system manual for detail.

(Refer to table below)

Component	System
ECM	Engine Control / Fuel System - Engine Control Module (ECM)
Seat belt switch	Restraint - Seat Belt Buckle Switch (BS)
Door switch	Body Electrical System - Keyless Entry And Burglar Alarm
Hood switch	Body Electrical System - Keyless Entry And Burglar Alarm
Brake switch	Brake System - Brake Switch
Brake booster vacuum pressure sensor	Brake System - Brake Booster
Ambient temperature sensor	Heating, Ventilation And Air Conditioning - Ambient Temperature Sensor
Battery sensor	Engine Electrical System - Battery Sensor
AGM battery	Engine Electrical System - Battery
DC DC converter	Engine Control / Fuel System - DC DC converter
Starter	Engine Electrical System - Starter
Position switch	DCT (Dual Clutch Transmission) System - Position Switch

•	ECM : Using all vehicle control system information, the ECM controls the Engine ON and OFF.

•	Seat belt switch : It detects the seat belt engagement and this information is used as the ISG system operating condition.

•	Door switch : It detects the driver side door open/close status and this information is used as the ISG system operating condition.

•	Hood switch: It detects the hood open/close status and this information is used as the ISG system operating condition.

•	Brake switch: It detects the brake pedal operation and this information is used as the ISG system operating condition.

•	Accelerator position sensor: It detects the accelerator pedal operation and this information is used as the ISG system operating condition. [when auto hold is applied]

•	Position switch : It detects the gear shift position (P/R/N/D, manual mode) and this information is used as the ISG system operating condition.

•	Brake booster vacuum pressure sensor : It detects the brake pressure and this information is used as the ISG system operating condition.

•	Ambient temperature sensor : It detects the ambient temperature and this information is used as the ISG system operating condition.

•	Batteryt sensor : If the battery sensor is deactivated, the ISG system does not work.

•

AGM battery : Due to more frequent engine start ON and OFF process than regular vehicles, the vehicles with ISG require the higher battery performance and the better battery state of charge management. Despite the high loads by frequent charging and discharging, AGM battery presents excellent durability.

Engine Control / Fuel System — ISG (Idle Stop & Go) System / Description and Operation / System Components illustration

•	DC/DC converter : The DC converter supplies the boosted voltage (12 ± 0.5V) to prevent electronic device (AVN or Audio, Cluster, etc.) reset from voltage drop at engine automatic start.

•	Starter : Vehicles with ISG are frequently engine ON/OFF, therefore starter motor with improved durability is applied.

•	ISG OFF switch : The ISG system is always ON whenever the engine starts, and can ISG system OFF by pressing the switch.

System Operating Condition

Division	Item			Condition
Auto start & Auto stop	Driver condition	ISG OFF switch		OFF
		Switch (Seat belt/Door/Hood)		Fastened/Closed/Closed
		Gear position		D/N
		Pedal condition (Brake)		Brake condition
				ON (Auto stop) / OFF (Auto start)
		Vehicle speed		Entering 0 kph (0 mph) after driving over 5 kph (3.1 mph).
		Climate control system condition		FATC/MTC Satisfied
		MDPS		Less than 180 degrees
	Battery condition	Charge/Discharge performance		SOC > 68 %
	Engine coolant temperature			20 - 43 °C (68 -109.4°F)
	Ambient air temperature			Ambient air temperature : -20 to 50°C (-4 to 122°F)
	Atmospheric pressure			More than 750 hPa (75 kph, 0.76 kg/cm², 10.88 psi)
	Brake vacuum pressure			Less than -35 kpa (-0.36 kg/cm², -5.07 psi)
	Incline condition			-5 to 12%
	ECM, TCU condition			Condition (temperature, error, OBD diagnosis) satisfied
	ISG related error			None
Forced restart	Climate control system condition	Blower MAX. / Front Defogger		ON
	Battery condition	Voltage		Insufficient charging and discharging performance
	Safety	Brake vacuum pressure		More than -35 kpa (-0.36 kg/cm², -5.07 psi)
		Vehicle speed		More than 1.5 kph (0.9 mph)
		Switch	Seat belt/Door	Open during brake pedal ON
			Hood open	Start by using the key
				(Message appear on instrument cluster)
		Brake/Accel pedal ON at the same time		Immediately restart
	ISG OFF switch			Immediately restart

ISG (Idle Stop & Go) System

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Kia Sorento: Description and Operation

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