Kia Rio: Engine Control / Fuel System / ISG (Idle Stop & Go) System

Components and components location

Description and operation

Idle Stop & Go (ISG) system switches off the ignition when vehicle is stopped, and then restarts the ignition and starts the vehicle when accelerator is pushed. It temporarily stops the engine while waiting for signal or idling to improve fuel efficiency and reduce exhaust gas emission. However, ISG system may not operate if engine oil or ambient temperature is too low, or if 12V battery voltage is too low. The system can be deactivated by pushing the ISG OFF switch when the driver wishes not to use ISG system.

Sample scenario: switching off the engine at a standstill at a red traffic light or in a traffic with frequent stops.

Battery Sensor

The battery sensor perceives battery status. Battery status is a major influencing factor on the ISG function. Its main purpose is to ensure a reliable start of the combustion engine after a defined parking period from the perspective of the vehicle energy system.

The Battery sensor monitors the following data:

Brake Booster Vacuum Pressure Sensor

In order to ensure adequate brake power assistance in every situation, the brake booster is equipped with a partial vacuum sensor. The brake booster vacuum pressure sensor is located beside the brake booster.

With an excessively low brake particl vacuum, the ISG function is activated without any action on the part of the driver. Insufficient brake partial vacuum can lead to safety risks during braking manoeuvres when rolling on an inclination. To prevent this, the engine will be started.

AGM battery

In all cases, the ISG function comes with the intelligent alternator control. As vehicles equipped with ISG experience more frequent charge and discharge cycles, the load on the battery is very high. The cycle resistance of AGM batteries means that they achieve similar results with regard to service life despite the high load.

Ensure that an AGM battery is fitted. In all cases, an AGM battery must be installed and registered in the vehicle for the ISG function to work perfectly.

DC/DC converter

Due to the considerably more frequent occurrence of starting operations, the electrical load that occurs often leads to voltage dips in the vehicle network. In order to stabilize the power supply for certain voltage-sensitive electrical components, a DC/DC converter is used in conjunction with the ISG function.

The DC/DC converter supplies the relay with a voltage that also remains constant during the starting operation.

The DC/DC converter is fitted at the back of the glove box.

Via the test leads for input voltage and the start relay , the electronics decide whether the power is supplied to the output via the bypass or the DC/DC converter.

In the bypass mode, the on-board supply voltage is not fed across the DC/DC converter and rather is transferred directly to the outputs. In the booster phase, the vehicle voltage is adapted.

ISG OFF Switch

The ISG OFF switch on the crashpad lower panel can be used to deactivate the ISG function.

Alternator

The battery discharge during the engine shutdown by the ISG function means that a more powerful alternator is installed.

Starter Motor

In conjunction with the ISG function, the starter motor must perform a great deal more work. The starter motor is therefore configured for a significantly higher number of start cycles. The components of the starter motor have been adapted to the higher requirements.

Neutral Switch

The neutral switch is mounted on top of the transmission case.

The neutral switch detects the idle position of the gearstick.

Clutch Switch

The present clutch switch is used as an input variable for the ISG function to detect clutch operation.

Seat Belt/door Switch (Driver)

By the seat belt/Door switch, the ISG function can detect if the driver has fastened the seat belt/closed the door. If the driver has not fastened the seat belt/closed the door, the ISG function will react as follows. If the seat belt is not fastened or a door is open, the engine will not start or stop by the ISG function for safety reasons.

Hood switch

The hood switch is one of the influencing factors of determining the activation of ISG function. If the hood is open, the engine will not start or stop by the ISG function for safety reasons.

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. They are only available again a closed-circuit current measurement of approximate 4 hours in which the vehicle may not be wakened. In this time, the ISG system is inactive.

After every engine start, the function is automatically activated on stand-by. The ISG OFF switch can be used to deactivate the function manually until the next terminal change. The indication lamp lights up to confirm pressing of the switch.

▶ Common Condition : Neutral Status & Clutch Pedal Released

▶ Common Condition : Neutral Status & Clutch Pedal Pressed

In case of error in idle stop status, the engine can be started by the key only.

The engine will start automatically without the driver's action if any of the following occurs:

▶ Common Condition : Neutral Status & Clutch Pedal Released

ISG system deactivated by fault – Faulty communication line (LIN/CAN) – Faulty neutral switch – Faulty brake booster vacuum pressure sensor – Faulty clutch switch When the ISG related sensors or system error occurs, the ISG OFF switch lights up. Especially, when the battery sensor has been replaced or reinstalled, the vehicle must be placed in ignition OFF for about 4 hours for recalibration. The ISG function will operate normally after 4 hours.

When the engine is in Idle stop mode, it's possible to restart the engine 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.

Troubleshooting

If the ISG function does not operate in spite of no DTC, inspect the ISG system as below.

The KDS/GDS shows the current data about the ISG function for inspection.

• ISG OFF switch