Auto Idle Stop System Description (2024 2025)
Overview
System Description
The auto idle stop system is a system that stops and restarts the engine automatically to help maximize fuel economy depending on environmental and vehicle operating conditions.The system can help reduce fuel consumption, idling noise and any emissions.Conditions such as driver's operation, vehicle state, and environment determines if the vehicle can enter auto idle stop.
Basic System Operations
- When the brake pedal is depressed, the vehicle stops and auto idle stop is activated (if conditions are met). During auto idle stop, the auto idle stop system indicator (green) indicator turns on in the gauge control module. When you release the brake pedal, the engine starts automatically (if conditions are met).
- The auto idle stop system is executed when the certain conditions are met. Refer to the Available Conditions for Auto Idle Stop.
- If one of the conditions are met, the engine restarts automatically. However, there are conditions that will prohibit the engine to start automatically. Refer to Engine Restart Conditions After Auto Idle Stop and Disable Conditions for the Engine Restart After Auto Idle Stop.
- The driver can cancel the auto idle stop system from operating with the auto idle stop off switch.
- When the system is off, the auto idle stop system indicator (amber) in the gauge control module turns on.
Auto Idle Stop Indicator
System Determination Pattern
After the vehicle is turned to the ON mode, the system is activated and starts a constant monitor of various conditions. The system then determines if a auto idle stop or an engine restart (after the engine has stopped) can be executed.
Auto idle stop at full stop (vehicle speed is 0 mph (0 km/h))
Auto Idle Stop Control Signal
The PCM monitors signals from control units, sensors and switches to determine if the vehicle can execute/continue an auto idle stop or if it can restart the engine. When the PCM determines that the auto idle stop can executed, it stops the fuel injection and stops the engine. When it determines an engine restart, it operates the starter and resumes fuel injection to start the engine. If the PCM receives a malfunction signal from a control unit or the conditions are not met, the auto idle stop is not executed.
Transmitting and Received Signals to/from the PCM
| Target unit, sensor and switch | Transmitting Signal | Received Signal | Remarks |
|---|---|---|---|
| Related control units | System malfunction signal | - | See detailed information |
| Idle stop off switch | Auto idle stop cancellation signal | - | - |
| Target unit, sensor and switch | Transmitting Signal | Received Signal | Remarks |
|---|---|---|---|
| Snow switch | Snow mode selected signal | - | - |
| Hood latch switch | Hood open/close signal | - | - |
| Driver's seat belt switch | Seat belt latched/unlatched signal | - | - |
| EPS control unit |
|
- | - |
| SBW shifter control module | Shift position information | - | - |
| TCM (Countershaft speed sensor) | Vehicle speed/vehicle speed record information | - | The signal is sent to the TCM. The TCM sends the determination of the auto idle stop system to the PCM based on the signal. |
| TCM (ATF temperature sensor) | ATF temperature information | - | The signal is sent to the TCM. The TCM sends the determination of the auto idle stop system to the PCM based on the signal. |
| TCM | Transmission status information
|
Engine status information
|
- |
| Brake pedal position switch | Brake pedal on/off signal | - | - |
| VSA modulator-control unit |
|
Starting Assist Brake request signal | See detailed information |
| SRS unit | Vehicle inclination angle information | - | - |
| Brake booster pressure sensor | Brake booster pressure information | - | - |
| Accelerator pedal module (APP sensor) | Accelerator pedal on/off signal | - | - |
| Engine coolant temperature (ECT) sensor | Engine temperature information | - | - |
| Barometric pressure (BARO) sensor | Atmospheric pressure (altitude) information | - | - |
| Climate control unit | Auto idle stop permission signal by the climate control system | - | See Detail Information of the Control or Communication Signal |
| Starter | - | Starter operating command signal | See Detail Information of the Control or Communication Signal |
| 12 volt battery sensor | 12 volt battery status information
|
- | See Detail Information of the Control or Communication Signal |
| DC-DC converter | Unit quality information | - | See detailed information |
| Target unit, sensor and switch | Transmitting Signal | Received Signal | Remarks |
|---|---|---|---|
| Gauge control module | - |
|
During auto idle stop:
When the idle stop system off switch is on:
When the idle stop system is failure:
|
| Injector | - | Fuel injection stop/injection command signal | - |
| Alternator | - | Alternator operating command | - |
Detail Information of the Control or Communication Signal
System Malfunction Signal
If there is a malfunction in the auto idle stop system and related systems, a message is displayed on the multi-information display in addition to the related system warning indicator and the auto idle stop system indicator (amber blinks).
Master Cylinder Fluid Pressure Information
The master cylinder fluid pressure information is transmitted to the PCM via the VSA modulator-control unit. If the brake pedal force by the driver is insufficient, and if the master cylinder fluid pressure is less than specified value, the auto idle stop is prohibited. In this case, a message is displayed in the gauge control module (multi-information display) to inform the driver.
Idle Stop Permission Signal from the Climate Control System
The climate control unit integrates with signals from some sensors and switches for maintaining cabin comfort, and sends determined signal which is the execution/prohibition of auto idle stop or the continuing auto idle stop (retained)/engine restart to the PCM.
Transmitting and received signals to/from climate control unit
| Target unit, sensor and switch | Transmitting Signal | Received Signal |
|---|---|---|
| ECON switch | ECON ON/OFF mode selection signal | - |
| Engine coolant temperature (ECT) sensor | Engine warm-up information | - |
| Windshield defrost button/switch | Windshield defrost on/off signal | - |
| Temperature and fan control button/switch (climate control unit) | Cabin temperature and air volume setting information | - |
| Outside air temperature sensor | Outside air temperature information | - |
| Rear A/C control panel | Cabin temperature and air volume setting information | - |
| Evaporator temperature sensor/in-car temperature sensor | Air temperature adjustments made before and after | - |
| Humidity sensor | Humidity information in the cabin | - |
| Sunlight sensor | Sunlight information | - |
| PCM | - | Auto idle stop implementation/prohibition determination information from the climate control system. |
Starter Operating Command Signal
The PCM is equipped with a start counter of the starter. The start counter counts up every time the starter is started, and when it reaches the upper limit of the assumed durability of the starting system parts, the PCM sends a warning signal to the gauge control module. After replacing the specified parts of the starting system, the warning signal is canceled by clearing the counter (reset to 0) with the HDS.
12 Volt Battery Status Information
The PCM counts the number of times that the start operates and if it exceeds a specified number, prohibits auto idle stop operation. In this case, the indicator on the gauge control module blinks (except when the system is turned off by the driver manually). The starter and the starter cut relay operation number are memorized in the PCM.
DC-DC Converter Unit Quality Information
The DC-DC converter supplies stable power to the vehicle when the battery voltage drops during engine restart. If there is a malfunction in the DC-DC converter, a signal is sent to the PCM and either prohibits the auto idle stop operation or engine restart. If the DC-DC converter malfunctions during engine restart, the starter operation continues but the stable power that the vehicle would have received from the DC-DC converter is not supplied.
Simple Circuit Diagram for Description
Pressurization Graphic by the DC-DC converter