Kia Rio YB Quiz
Engine Control System/Fuel System

ISG (Idle Stop & Go) System

In this manual: Engine Control System/Fuel System
General Information — 8Maintenance — 31Engine Mechanical System — 44Engine Electrical System — 14Emission Control System — 9Engine Control System/Fuel System — 30Clutch System — 10Manual Transmission — 10Automatic Transmission — 23Drive Shaft and Axle — 8Suspension System — 15Steering — 9Restraints — 14Brake System — 22Body (Interior and Exterior) — 115Body Electrical System — 84Heating, Ventilation, and Air Conditioning — 28
9steps
~54min
4/5difficulty
Done 0 of 9

Components and Component Location

Component Location

1. Battery Sensor
2. Brake Booster Vacuum Pressure Sensor (BBVPS)
3. AGM Battery
4. DC-DC Converter
5. ISG Switch
6. Generator		 7. Starter Motor
8. Neutral Switch
9. Clutch Switch
10. Door Switch
11. Seat Belt Switch
12. Hood Switch

1. Battery Sensor
3. AGM Battery		 2. Brake Booster Vacuum Pressure Sensor (BBVPS)
4. DC-DC Converter 5. ISG Switch
6. Alternator 7. Starter Motor
8. Neutral Switch 9. Clutch Switch
10. Door Switch 11. Seat Belt Switch
12. Hood Switch

Description and Operation

Description

The Idle Stop & Go (ISG) system shuts off the engine when the vehicle stops, and then restarts the engine and drives the vehicle when the accelerator pedal is depressed. It temporarily stops the engine while waiting at a signal or while idling to improve fuel efficiency and reduce exhaust emissions. However, the ISG system may not operate if the engine oil or ambient temperature is too low, or if the 12 V battery voltage is too low. The system can be deactivated by pressing the ISG OFF switch when the driver does not wish to use the ISG system.

Example scenario: Engine stops at a stop when waiting at a red traffic light or in stop-and-go traffic.

  1. The vehicle is moving.

  2. Gear engaged. Accelerator pedal depressed.

  3. Engine running.

  4. Driver brakes until the vehicle comes to a complete stop.

  5. The driver shifts into neutral and releases the clutch pedal.

  6. The engine stops. The "AUTO STOP" symbol illuminates on the instrument cluster.

  7. Driver wants to continue driving.

  8. The driver depresses the clutch pedal. The engine starts.

  9. The gear can be engaged and the journey continued. The "AUTO STOP" symbol goes off.

Battery Sensor

The battery sensor monitors the battery condition. Battery condition is the main factor affecting ISG function. Its main purpose is to ensure reliable restarting of the internal combustion engine after a certain period of standstill from the vehicle's power system standpoint.

The battery sensor monitors the following data:

  • Battery Charge Status

  • Battery Temperature

  • Voltage Dip During Engine Starting

Brake Booster Vacuum Pressure Sensor

To ensure adequate brake force assistance in any situation, the booster is equipped with a partial vacuum sensor. The brake booster vacuum sensor is located next to the brake booster.

AGM Battery

In all cases, the ISG function is supplied with intelligent generator control. Since vehicles equipped with ISG undergo charge and discharge cycles more frequently, the load on the battery is very high. The cycle durability of AGM batteries means that they achieve similar results in terms of service life despite the high load.

DC-DC Converter

Due to significantly more frequent starting, the resulting electrical load often causes voltage dips in the vehicle power network. To stabilize the power supply for some voltage-sensitive electrical components, a DC-to-DC converter is used in combination with the ISG function.

The DC-to-DC converter supplies a constant voltage to the relay, which also remains constant during the starting operation.

The DC-to-DC converter is installed at the rear of the glove box.

Through the measuring wires for the input voltage, the starter relay electronics determine whether power is supplied to the output via the bypass or the DC/DC converter.

In bypass mode, the vehicle power network voltage is not supplied through the DC-to-DC converter, but is transmitted directly to the outputs. During the acceleration phase, the vehicle voltage is adapted.

ISG switch

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

Generator

Battery discharge while the engine is stopped by the ISG function means that a more powerful generator is installed.

Starter motor

In combination with the ISG function, the starter must perform considerably more work. Therefore, the starter is designed for a significantly higher number of starting cycles. The starter components are adapted to these higher requirements.

Neutral Switch

The neutral switch is installed at the top of the transmission case.

The neutral switch detects the idle position of the shift lever.

Clutch Switch

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

Seat Belt / Door Switch (Driver)

Using the seat belt and door switch signals, the ISG function can determine whether the driver has fastened the seat belt and closed the door. If the driver has not fastened the seat belt or closed the door, the ISG function will respond as follows. If the seat belt is not fastened or the 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 factors that affect the activation determination of the ISG function. If the hood is open, the engine will not start or stop by the ISG system for safety reasons.

Operating conditions for ISG function

After each engine start, the function is automatically activated. The ISG OFF switch can be used to deactivate the function manually until the next ignition cycle. The indicator lamp illuminates to confirm that the switch has been pressed.

1. Idle stop condition (Idle → Stop)

▶ General condition: Neutral position and clutch pedal released

Required conditions
Engine coolant temperature is not too low (above 45 °C).
No DPF regeneration
No inhibitor for operating strategy or engine malfunction

  • CKPS, CMPS, ECTS, VSS, battery sensor, BBVPS, neutral switch, clutch switch, APS, injector
Battery charge state is sufficiently high.
No communication line error - LIN, CAN
Vehicle speed below 5 km/h
Vehicle speed exceeds 10 km/h at least once after key-on or idle start
ISG OFF switch OFF
Driver seat belt, driver door and hood are closed.
Battery 2 temperature - 55 °C.
Brake booster pressure is not too low.
Fan not at maximum

2. Idle stop condition (Stop → Start)

▶ General condition: Neutral position and clutch pedal depressed

Required conditions
Inhibitor for operating strategy in unsatisfactory condition or engine malfunction

  • CKPS, CMPS, ECTS, VSS, battery sensor, neutral switch, clutch switch, APS
No communication line error - LIN, CAN
Driver seat belt, driver door and hood are closed.
Engine stalled, the shift lever was moved from a gear to neutral, and the clutch pedal was depressed.

3. Auto start condition (Stop → Start)

The engine will start automatically without driver intervention if any of the following occurs:

▶ General condition: Neutral position and clutch pedal released

Required conditions
No inhibitor condition for operating strategy

  • TPS, CKPS, CMPS, ECTS, VSS, battery sensor, BBVPS, neutral switch, clutch switch
Brake booster vacuum pressure is low.
When battery charge level is low.
After A/C is turned on, a certain time has elapsed.
Vehicle speed greater than 5 km/h on a downhill grade.
Maximum fan speed

Troubleshooting

Troubleshooting

If the ISG function does not operate although no DTC is stored, inspect the ISG system as shown below.

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

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