DRIVE-BY-WIRE CONTROL OPERATION [MZR 1.3, MZR 1.5]

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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 (MTX)	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 amplifier (A/C switch) ― Refrigerant pressure switch (middle)	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.	Correction amount increases as the ignition timing retard for the warm-up promotion spark retard correction of the ignition timing control advances.

Accelerator Control

• With the 55 kW 1.3GE and 63 kW 1.3GE engine specification models, the two output characteristics have been achieved by changing the throttle valve opening angle according to the amount of accelerator depression. (ZJ European (L.H.D. U.K. specs.)

• 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 switch is 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 switch is off, a main relay on request is output and the fully-closed learning function is executed.

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 sends a duty signal to 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).

― Cruise control 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 switch: OFF

― Cruise control OFF switch: ON

― Cruise control related DTCs (P0564:00, 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

― TR switch: P/N position switch: ON (ATX)

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

― Brake switch No.1, No.2: ON

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

― Condition where actual vehicle speed is 15 km/h {9.3 mph} or more lower than the set vehicle speed continues for 60 s or more even when the RESUME switch is on.

Cruise control function

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

Function List

Function	Contents
Accelerating	• When the SET+ switch is continuously pressed, the PCM gradually the set vehicle speed.
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 km/h {0.6 mph} (Australia)/ 1.6 km/h {0.99 mph} (Except for Australia) and controls the throttle valve actuator. ― 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})
Tap-up	• When all of the following conditions are met, the PCM increases the set vehicle speed by 1 km/h {0.6 mph} (Australia)/ 1.6 km/h {0.99 mph} (Except for Australia) and controls the throttle valve actuator. ― 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. ― RESUME switch or SET+ switch on ― Target vehicle acceleration is not reached

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

Operation of brake override system

• In the event of any malfunction in the accelerator system, the vehicle is equipped with a sub-system that prioritizes the brake operation over the accelerator pedal operation. Specifically, the sub-system functions to close throttle valve when the brake pedal is depressed while the accelerator pedal is depressed to safely decelerate the vehicle to a full stop.

Brake override operation conditions

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

While driving vehicle

―  Accelerator pedal opening angle: 5% or more from fully-closed

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

―  In gear

―  Engine speed: 1,150 rpm or more

While vehicle stopped

―  Accelerator pedal opening angle: 5% or more from fully-closed

―  Shift lever position: neutral (MTX)

―  Selector lever position: N position (ATX, CVT)

―  Engine speed: 1,150 rpm or more

End brake override operation

•  To return the throttle to normal operation, the following conditions must be met.

―  Accelerator pedal is not depressed

―  Brake pedal is not depressed

Note

•  Cycling the key off and back on will also end brake override operation.

* :For MTX vehicles, engine speed is 1,200 rpm when in neutral, and 1,100 rpm when not in neutral. For ATX, CVT vehicles, engine speed is 1,200 rpm when in N position, and 1,100 rpm when in D position.

Disabling of brake override system

• If the servicing procedure requiring the brake pedal and the accelerator pedal to be depressed together, operation of the brake override system can be prevented, if necessary.

Disable brake override operation conditions

•  If the following conditions are met for 10 s within 30 s after switching the ignition ON (engine off), the brake override system is disabled until the activate brake override operation conditions are met.

―  Vehicle speed: 0 km/h {0 mph}

―  Accelerator pedal fully depressed

―  Brake pedal depressed

Activate brake override operation conditions

•  Cycling the key off and back on will activate the brake override operation conditions.

Brake warning light illumination request (vehicles without malfunction warning light)

• If the following condition is met, the PCM sends the brake warning light illumination request signal to the instrument cluster. The brake 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

Malfunction warning light illumination request (vehicles with malfunction warning light)

• If the following condition 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

Disable brake override operation conditions	• If the following conditions are met for 10 s within 30 s after switching the ignition ON (engine off), the brake override system is disabled until the activate brake override operation conditions are met. ― Vehicle speed: 0 km/h {0 mph} ― Accelerator pedal fully depressed ― Brake pedal depressed
Activate brake override operation conditions	• Cycling the key off and back on will activate the brake override operation conditions.