DRIVE-BY-WIRE CONTROL OPERATION [L8, LF]

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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
--- | --- | --- | ---
Correction | Target | Conditions | Correction amount
A/C load correction | Prevents decrease in idle speed due to A/C operation. | A/C is operating. | A/C operation time→correction
Electrical load correction | Prevents decrease in idle speed due to electrical load operation. | Idle speed during electrical load operation and under any condition during driving | High electrical load→large correction
D-range correction (AT) | Prevents decrease in idle speed due to shifting into D-range | D-range signal is input. | Low idle speed when shifted to D range→large correction
Dashpot correction | Prevents decrease in idle speed due to insufficient intake air amount during deceleration. | Decelerated | High engine speed→large correction
Correction at engine start | Prevents decrease in idle speed after engine start. | After cranking and engine start | Low ECT→large correction
Hot engine restart correction | Prevents decrease in idle speed from hot engine restart. | Just after cranking and engine start when the ECT is 60 °C {140 °F} or more the IAT is 50 °C {122 °F} or more | High intake airflow temperature→large correction
Feedback correction A | Sets idle speed to target engine speed. | Idle speed during idling (vehicle is stopped) is over or under the target engine speed (except during test mode when the engine speed is 300 rpm or less). | Actual idle speed Target engine speed or less→volume increase correction Target engine speed or more→volume decrease correction
Feedback correction B | Sets to the target engine speed when the idle speed has decreased in the range not corrected by feedback correction A, and prevents a decrease in idle speed. | During deceleration at fully closed throttle, the engine speed is the target engine speed or more and when the feedback correction A is not performed (except during test mode). | Large difference between actual idle speed and target engine speed→large correction
Engaged coasting clutch volume increase correction | Reduces shock when the transaxle coasting clutch is engaged. | When coasting clutch is engaged. | High vehicle speed→large correction
Learning correction | Stores intake air volume changes based on differences between engines and changes due to aged deterioration, and feedback. | During feedback correction A when ECT is 85 °C {185 °F} or more. | During idling→average value of feedback correction A

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 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. (See MAIN RELAY CONTROL OPERATION [L8, LF].)

Traction Control

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

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.

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• 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 OFF switch: ON
    ― Vehicle speed: More than 27 km/h {17 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 ON OFF switch: OFF

  • 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.
    ― Cruise control CANCEL switch: ON
    ― Neutral switch (MT) or CPP switch (MT): ON
    ― TR switch (AT) P/N position switch: ON
    ― Vehicle speed: Less than 22.5 km/h {13.9 mph}
    ― Brake switch: 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 RES/+ switch is on.

Cruise control function

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

Function List

Function | Contents
--- | ---
Accelerating | • When any of the following conditions are met while driving in cruise control and when the RES/+ switch is continuously pressed, the PCM gradually increases the set vehicle speed. ― Except during resume operation ― The RES/+ 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 RES/+ 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 {1.0 mph} and controls the throttle valve actuator. ― During cruise control ― RES/+ switch off ― The RES/+ switch switches from off to on ― When actual vehicle speed is lower (set vehicle speed +2.0 km/h {+1.2 mph})
Tap-up | • When all of the following conditions are met, the PCM increases the set vehicle speed by 1.6 km/h {1.0 mph} and controls the throttle valve actuator so that the vehicle speed is close to the set vehicle speed. ― During cruise control ― The RES/+ switch switches from off to on
Downshift (AT) | • When the following conditions are met, a downshift signal is sent to the TCM via CAN. ― RES/+ switch on ― Target vehicle acceleration is not reached

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.

Brake Override System (From NC18**-215550,NC18**-250831,NC30**-202488,NCA8**-251024)

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 (MT) ― Selector lever position: N position (AT) ― 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 MT vehicles, engine speed is 1,200 rpm when in neutral, and 1,100 rpm when not in neutral. For AT 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. ― Shift lever position: neutral (MT) ― Selector lever position: N position (AT) ― 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