DRIVE-BY-WIRE CONTROL [SKYACTIV-G 2.0]

id0140f4188400

Outline

• Calculates the optimum target throttle valve opening angle at all engine speeds and controls the throttle valve actuator.

• The drive-by-wire control is composed of the idle air control, accelerator control, traction control, excess engine speed control, overspeed control, electric variable valve timing cooperation control, and the brake override system.

Control Table

Control name	Control outline
Idle air control	• While idling, the throttle valve opening is controlled so that the idle speed is at the target idle speed.
Accelerator control	• The throttle valve opening angle is controlled according to the amount the accelerator pedal is depressed. In addition, there is a fully closed learning function for learning deterioration over time and constant correction of the optimum throttle opening angle.
Traction control	• The throttle valve opening angle is controlled by the torque reduction request signal from the DSC HU/CM and TCM.
Excess engine speed control	• If the engine reaches a high engine speed, the throttle valve opening angle is controlled to protect the engine.
Overspeed control	• If the vehicle reaches a high speed, the throttle valve is closed to keep the vehicle speed below the speed limit.
Electric variable valve timing cooperation control	• Pumping loss is reduced by controlling the throttle valve timing opening angle according to the phase of the intake valve timing.
Cruise control (With cruise control system)	• Sets the vehicle speed by operation of the cruise control switch and controls the throttle valve opening angle so that it becomes close to the set vehicle speed.
Brake override system	• If the brake pedal is depressed with the accelerator pedal depressed, the vehicle can be stopped safely by closing the throttle valve. As a result, the brake operation takes priority over the accelerator pedal operation.

Block Diagram

am3zzn00003359

Operation

Idle air control

• The throttle valve opening angle is controlled so that the idle speed is at the target idle speed calculated by the PCM.

• The PCM determines the basic duty value (throttle valve opening angle basic) according to target engine speed. Corrections are added to the basic air amount, the target throttle valve opening angle is calculated, and the duty signal is sent to the throttle valve actuator.

• Corrections are as follows: The throttle valve opening angle increases as the corrections increase.

Correction list

Correction	Purpose	Vehicle condition	Correction amount
Engine coolant temperature correction	Corrects the fluctuation in engine sliding resistance due to change in engine temperature.	Correction amount is determined according to engine coolant temperature.	Low engine coolant temperature→large correction
Start correction	Prevents decrease in idle speed during engine start.	Immediately after cranking and engine start	Low engine coolant temperature→large correction
Feedback correction	Sets idle speed close to target engine speed.	• When all of the following conditions are met, feedback correction is performed. ― Vehicle parked ― Accelerator pedal fully closed	Actual idle speed Target engine speed or less→volume increase correction Target engine speed or more→volume decrease correction
Learning correction	Corrects the changes in the air flow amount caused by engine deterioration over time such as engine sliding resistance and air leakage from the throttle valve.	Correction amount is determined according to the feedback correction amount while external load correction and purge control are stopped.	If the maximum or minimum value of feedback correction exceeds the specified value, learning correction is performed.
Evaporative purge correction	Air increased by purge control is subtracted from the target throttle opening angle.	Correction amount is determined according to purge flow amount during purge control execution.	Large purge flow amount→small correction
External load correction	• Prevents decrease in engine speed due to A/C and electrical load operation. • Prevents sudden increase in engine rotation due to A/C and electrical load operation stop.	• When any of the following signals is input: ― A/C amplifier ― A/C pressure signal ― Generator output current	Large external load→large correction
Fast idle increase correction^*	Activates the catalytic converter earlier after starting cold engine.	Integrates warm-up promotion spark retard correction for ignition timing control. (See ELECTRONIC SPARK ADVANCE CONTROL [SKYACTIV-G 2.0].)	Warm-up promotion spark retard for ignition timing control large→large correction
Hot engine restart correction	Prevents decrease in idle speed due to hot engine restart.	Just after cranking and engine start when the engine coolant temperature is 60 °C {140 °F} or more and intake air temperature is 50 °C {122 °F} or more.	High intake airflow temperature→large correction
D-range correction	Prevents decrease in idle speed due to shifting into D-range	When D range signal (transaxle range sensor) is input	Large D range load→large correction

* :Engine speed increases up to approx. 2,000 rpm.

Accelerator control

• The accelerator control controls the throttle valve opening angle according to the accelerator pedal depression amount.

• The PCM controls the throttle valve actuator so that the actual throttle valve opening angle approaches the final target throttle valve opening angle.

• The target throttle valve opening angle is determined by the transmission gear position, accelerator pedal depression amount, and vehicle speed.

• Because deviation in the throttle valve opening angle due to deterioration over time is corrected when the ignition is switched off, the PCM operates the fully-closed learning function. The fully-closed learning function is a function for learning the fully-closed throttle valve position.

Traction control

• The PCM calculates the target throttle valve opening angle based on torque reduction request signal and engine speed from the DSC HU/CM and TCM.

Excess engine speed control

• If the engine reaches a high engine speed, the engine speed stabilizes at a lower speed than the excess speed range to protect the engine.

Overspeed control

• If the vehicle reaches a high speed, the throttle valve is closed to keep the vehicle speed below the speed limit.

Electric variable valve timing cooperation control

• The PCM calculates the target throttle valve opening angle according to change in the phase of the intake valve timing due to electrical variable valve timing control.

Cruise Control (With Cruise Control System)

• Calculates the throttle valve opening angle based on the deviation of the actual vehicle speed from the set vehicle speed which was set with the cruise control switch and the throttle valve actuator.

• The PCM controls the actual vehicle speed so that it is close to the set vehicle speed.

• The cruise control includes the cruise control operation condition and the cruise control stop condition.

Cruise control operation condition

• When all of the following conditions are met, execution of the cruise control system is enabled (cruise control standby status).

• ON switch: ON

• Vehicle speed: Exceeds 25 km/h {16 mph}

Cruise control stop condition

• When any of the following conditions are met even while in cruise control, the PCM stops the cruise control and clears the set vehicle speed.

― Ignition: OFF

― ON switch: OFF

― Cruise control related DTCs (P0571:00) detected

• When any of the following conditions are met even while in cruise control, the PCM stops the cruise control while storing the set vehicle speed.

― CANCEL switch: ON

― Transaxle range sensor: P/N position

― Vehicle speed: Less than 20.5 km/h {12.7 mph}

― Brake switch: ON (brake pedal depressed)

― The actual vehicle speed is 15 km/h {9.3 mph} or more lower than the set vehicle speed during cruise control (ascending).

Cruise control function

• The cruise control includes accelerating, coasting, resume, tap-down, tap-up and downshift functions.

Function List

Function	Contents
Accelerating	• When any of the following conditions are met while driving in cruise control and when the SET+ switch is continuously pressed, the PCM gradually increases the set vehicle speed. ― The SET+ switch is on one time or more during resume operation.
Coasting	• When the SET- switch is continuously pressed, the PCM gradually decreases the set vehicle speed.
Resume	• When the RESUME switch signal is input to the PCM during regular driving (cruise control is stopped) and the previously set vehicle speed is stored in the PCM, the PCM sets the set vehicle speed to the previously set vehicle speed and begins control.
Tap down	• When all of the following conditions are met while driving in cruise control, the PCM decreases the set vehicle speed by 1.6 km/h {0.99 mph}. ― SET+ switch off ― The SET- switch switches from off to on ― When actual vehicle speed is lower (set vehicle speed +2 km/h {+1 mph})
Tap-up	• When all of the following conditions are met, the PCM increases the set vehicle speed by 1.6 km/h {0.99 mph}. ― During cruise control ― The SET+ switch switches from off to on ― When actual vehicle speed is lower (set vehicle speed +2 km/h {+1 mph})
Downshift	• When the following conditions are met, a downshift signal is sent to the TCM (ATX) via CAN. ― SET+ switch on ― Target vehicle acceleration is not reached

Brake override system

Brake override system operation conditions

• It gives priority to the brake operation if a malfunction occurs with the accelerator pedal such as if the accelerator pedal is depressed and does not return. The throttle valve is closed if the brake pedal is depressed while the accelerator pedal is in a depressed condition until the vehicle is safely decelerated and comes to a complete stop.

Operation start conditions

•  If either one of the following conditions is met with the brake pedal depressed for the specified time^*1 or more while the accelerator pedal is depressed, the PCM adjusts the throttle valve opening angle so that the engine speed is at specification^*2.

While driving vehicle

―  Accelerator pedal opening angle: 5% or more from full-close

―  Vehicle speed: 10 km/h {6.2 mph} or more

―  Engine speed: 875 rpm or more

While vehicle stopped

―  Accelerator pedal opening angle: 5% or more from full-close

―  Selector lever position: N position

―  Engine speed: 875 rpm or more

Operation complete conditions

•  If the following conditions are met while operating the brake override system, the PCM stops the operation of the brake override system and controls the throttle valve opening angle in accordance with the accelerator pedal opening angle.

―  Accelerator pedal not depressed

―  Brake pedal not depressed

Note

•  The brake override system operation stops by switching the ignition off.

*1 :Specified time is 0.6 to 10 s according to braking force calculated in PCM.

*2 :Specification is 1,200 rpm while vehicle is stopped and 1,100 rpm while vehicle is driven.

Prevention of brake override system unnecessary operation

• If a servicing procedure requiring the brake pedal and the accelerator pedal to be depressed simultaneously is performed, unnecessary operation of the brake override system can be prevented, if necessary.

Cancel conditions

•  If the releasing procedure is implemented with the following conditions met within 30 s after switching the ignition ON (KOEO), the brake override system does not operate until the recovery condition is met.

―  Selector lever position: N position

―  Vehicle speed: 0 km/h {0 mph}

Releasing procedure

1.  Depress the brake pedal for 10 s with the accelerator pedal released.

2.  Repeatedly depress and release the accelerator pedal fully three times with the brake pedal depressed.

3.  Release the brake pedal.

Recovery condition

•  The cancel conditions are reset when the ignition is switched off while the brake override system is canceled. As a result, the brake override system can operate.

Malfunction warning light illumination request

• If any of the following conditions is met, the PCM sends the malfunction warning light illumination request signal to the instrument cluster. The malfunction warning light illuminates to alert the driver that there is a malfunction in the brake system.

― Brake switch No. 1 or 2 malfunction is detected

― Brake override system unnecessary operation is prevented