DRIVE-BY-WIRE CONTROL OPERATION [MZR 1.6]

id0140j7170600

Idle Speed Control

• Controls the throttle valve opening angle so that it is close to the target idle speed calculated by the PCM.

• The PCM calculates the target throttle opening angle by adding each type of correction to the basic duty value which is the basis of the throttle valve opening angle, and then sends a duty signal to the throttle valve actuator. The basic duty value is determined by the target engine speed.

• Each type of correction is as follows.

Correction

Correction	Purpose	Condition	Amount of Correction
Water temperature correction	Corrects changes in engine friction resistance based on changes in engine temperature.	Determines correction amount based on ECT.	Correction amount decreases as ECT increases.
Correction at engine start	Prevents idle speed dropping off after engine start.	Directly after cranking and engine-start.	Correction amount increases as ECT decreases.
Feedback correction	Performs feedback control so that idle speed is close to the target idle speed.	• Executes feedback conditions when all of the following conditions are met: ― Vehicle stopped ― AP fully closed	• Correction amount decreases when the idle speed is higher than the target idle speed. • Correction amount increases when the idle speed is lower than the target idle speed.
Learning correction	Corrects air flow amount changes from changes in the engine due to aged deterioration such as engine friction resistance and air leakage from the throttle valve.	Determined by the amount of feedback correction when external load correction and purge control stop.	Learning correction executed when upper or lower limit of feedback correction exceeds the fixed value.
Purge correction	Increase in air from purge control is subtracted from the target throttle opening angle. Increases throttle valve opening angle to prevent rotation fluctuation from changes in air/fuel ratio when purge concentration is high.	Determined by the purge flow amount and purge concentration when purge control is executed.	• Correction amount decreases as purge flow amount increases. • Correction amount increases as purge flow concentration increases.
Load correction when vehicle accelerates from idle	Prevents engine speed drop after vehicle accelerates from idle.	At acceleration from idle	The amount of correction increases as the idle speed depression amount increases.
External load correction	• Prevents engine speed drop when the A/C and electrical load are operating. • Prevents engine speed revving when the A/C and electrical load are off.	• When any of the following signals are input: ― A/C switch ― Refrigerant pressure sensor	Correction amount increases as external load increases.
Fast idle up correction	Rapidly activates the catalytic converter after cold-engine start.	Synchronizes warm-up promotion spark retard correction for electric spark control. (See ELECTRONIC SPARK ADVANCE OPERATION [MZR 1.6].)	Correction amount increases as the ignition timing retard for the warm-up promotion spark retard correction of the ignition timing control advances.

Accelerator Control

• Controls the throttle valve opening angle through control of the throttle valve actuator, according to the amount of AP depression.

• The PCM controls the throttle valve actuator so that the actual throttle valve opening angle is close to the target throttle valve opening angle.

• The final throttle valve opening angle is determined by the sum of the target throttle opening angle during idling and the target throttle valve opening angle during regular driving.

• The target throttle valve opening angle during regular driving is determined based on the transmission gear position, the amount of AP depression and the engine speed. If the target throttle opening angle is at the fixed value or less during regular driving, the PCM switches to idle speed control.

• The PCM sets the throttle valve to the fully-closed position when the ignition is switched on or off and executes the idle position learning function to learn the throttle valve position. Due to this, changes in the throttle valve opening angle due to age deterioration are corrected.

• When the ignition is switched off, a main relay on request is output and the fully-closed learning function is executed. (See MAIN RELAY CONTROL OPERATION [MZR 1.6].)

Traction Control

• The PCM calculates the target throttle valve opening angle by the torque up/down request signal from the TCM (ATX) and DSC HU/CM.

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

― OFF/CANCEL switch: On (long-press)

― 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.

― OFF/CANCEL switch: On

― Transaxle range sensor: P/N position (ATX)

― CPP switch: ON (clutch pedal depressed) (MTX)

― Neutral switch: ON (neutral position) (MTX)

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

― Brake switch: ON (brake pedal depressed)

― Brake fluid pressure: 0.3 MPa {3 kgf/cm², 44 psi} or more

― Actual vehicle speed is 15 km/h {9.3 mph} or more lower than the set vehicle speed during cruise control (during ascent)

― Parking brake lever pulled

Cruise control function

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

Function List

Function	Contents
Accelerating	• When the RESUME/+ switch is continuously pressed while driving in cruise control, the PCM gradually increases the set vehicle speed.
Coasting	• When the SET/- switch is continuously pressed while driving in cruise control, the PCM gradually decreases the set vehicle speed.
Resume	• When the RESUME/+ switch signal is send 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 km/m (speedometer displayed in [km/m])/1 mph (speedometer displayed in [mph]). ― RESUME/+ 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 km/m (speedometer displayed in [km/m])/1 mph (speedometer displayed in [mph]) and the throttle valve actuator is controlled so that the vehicle speed is close to the set vehicle speed. ― During cruise control ― The RESUME/+ 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. ― RESUME/+ switch on ― Target vehicle acceleration is not reached • If the increase in vehicle speed on the down slope is high, the PCM sends a down shift signal to the TCM (ATX).

Excess Engine Speed Control

• If the engine reaches a high engine speed, the following controls are performed to protect the engine:

1. To alert the driver that the engine speed has reached a high engine speed, the opening and closing of the throttle valve are repeated at regular intervals.

2. The engine speed stabilizes at a lower speed than the excessive speed zone.

3. If the engine speed reaches a high engine speed even if the above procedures are performed, a forced shift-up is performed to lower the engine speed. (ATX only)

Excess Vehicle Speed Control

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

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: 1,150 rpm or more

While vehicle stopped

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

―  Shift position: neutral (MTX)

―  Selector lever position: N position (ATX)

―  Engine speed: 1,150 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

Note

• The operation of the emergency signal system (ESS) can be also canceled by performing the procedure for preventing unnecessary operation of the brake override system.

• 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.

―  Shift position: neutral (MTX)

―  Selector lever position: N position (ATX)

―  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.

Master warning light illumination request

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

― Brake switch (No.1 signal) has a malfunction

― Brake switch (No.2 signal) has a malfunction

― Brake override system unnecessary operation is prevented