Hyundai Tucson: ISG (Idle Stop & Go) System / Repair procedures

- Operating Condition for the ISG function 1. Auto stop or Auto start condition ▶ If all of the below conditions are satisfied

   

• If the following conditions are not met, entry into the ISG system is prohibited.

Component	Conditions		Remark
	AT	MT
ISG OFF Switch	OFF	OFF	ISG OFF switch indicator lamp ->OFF
Drive door / Seat belt / Hood	Closed	Closed
Gear state	D range or N range	Neutral	When gear is shifted to R, entry into the ISG system is prohibited.
Brake pedal	ON (Auto Stop) / OFF (Auto Start)	-
Clutch pedal	-	OFF (Auto Stop) / ON (Auto Start)
Vehicle speed	When entering below 0 kph after driving above 5 kph.	When entering below 5 kph after driving above 10 kph.	Idle stop is possible when shifting the gear from D to N after stopping (allowed only once)
A/C System	When conditions of full auto air conditioner/manual air conditioner are satisfied	When conditions of full auto air conditioner/manual air conditioner are satisfied	Outside temperature is within -20 - 50 degrees
MDPS	Within 180 degrees	No limit
RR Defogger switch	Gasoline : OFF / Diesel : irrelevant	Gasoline : OFF / Diesel : irrelevant
Battery (Charge / discharge)	Over SOC 68%	Over SOC 68%
Engine Coolant Temperature	Gasoline : 70 - 75°C / Diesel : 20 - 30°C		Different depending on the region and vehicle model
Ambient pressure	Over 750hPa	No limit
Slope	From -5 to 12% (some SUV's are from -5 to 8%)	No limit
ECM / TCM	When conditions (temperature, DTCs, OBD diagnosis, etc.) are satisfied		In case of diesel, ISG operation is prohibited when regenerating the DPF.
ISG system error	No occurred

   

• In congested areas, if the driver wishes to stop the vehicle and change lever from D→N, the ignition will turn OFF.

2. Conditions for forced restart (If none of the below condition is not satisfied)

Component	Conditions		Remark
	AT	MT
A/C System (Blower Max)	ON	ON	If more than 5/8, it is judged as max
RR Defogger switch	ON	ON
Comfortable	Full auto air conditioner/manual air conditioner request	Full auto air conditioner/manual air conditioner request	Based on the evaporator temperature and time
Battery voltage	If the charge/discharge performance are not satisfied	If the charge/discharge performance are not satisfied	Different depending on the region and vehicle model
Brake vacumm	Over -35 kPa	Over -35 kPa
Vehicle speed	Over 1.5 kph	Over 6 kph
Seat / Door	When opened during brake pedal On.	None (The message is displayed on the instrument cluster)	Ensuring safety
Hood	Engine start with key when the hood is opened	None (The message is displayed on the instrument cluster)
When operating the brake and accelerator simultaneously	Engine is restarted immediately	-
ISG OFF Switch	Engine is restarted immediately	-

   

• When the battery negative (-) terminal is disconnected, the battery sensor is deactivated. So, after reinstalling the battery sensor, make sure to activate it.

• The battery sensor is activated when the vehicle is left in parking status for about 4 hours after battery negative (-) terminal is connected to the battery.

• Even if the battery sensor is deactivated, the ISG may operate restrictively but for normal ISG operation, the battery sensor must be activated.

   

ISG system deactivation by fault.

– Fault in communication line (LIN/CAN)

– Fault Brake switch

– Fault brake booster vacuum pressure sensor

– When starter motor needs to be replaced as its life has ended due to the use of ISG for a long period of time

As stated above, if the sensors and parts related to the ISG are faulty or system error occurs, the ISG indicator (yellow) will blink for 5 seconds then remains ON and the message "Check Engine Auto Stop System" is displayed on the instrument cluster. At this time, the ISG OFF switch indicator turns ON. Especially, when the battery sensor is reinstalled after replacing or removing it, ISG system will operate normally as battery sensor becomes normal after the vehicle is left in parking status for about 4 hours. However, when keeping the ignition switch OFF condition after extracting the key, power lines of all the personal electrical devices (ex: navigation, black box, etc) must be disconnected other than the standard electrical devices installed in assembly line.(However, it may take a long time depending on the vehicle condition)

   

• 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.