#
DRIVE-BY-WIRE CONTROL OPERATION

BHE014000140T12

## 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 (MT) | 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 (medium-pressure switch) – Generator current value | Correction amount increases as external load increases.
Fast idle up correction | Rapidly activates the catalytic converter after cold-engine start. | Synchronizes fast idle correction for electric advance control. (See ELECTRIC SPARK ADVANCE CONTROL OPERATION.) | Correction amount increases as the ignition timing retard for the fast idling 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 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.)

## 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.

1 | Standby
2 | Vehicle speed setting
3 | Acceleration
4 | Deceleration
5 | Standby
6 | Resume
7 | Set vehicle speed
8 | Vehicle speed 0 km/h {0mph}
9 | ON/OFF
10 | RES ACCEL
11 | SET COAST
12 | CANCEL
13 | ON
14 | OFF
15 | ACCEL
16 | TAP UP
17 | RES
18 | SET
19 | COAST
20 | TAP DOWN
21 | CANCEL
22 | Actual vehicle speed
23 | 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 main switch: ON
  – Vehicle speed: Exceeds 27 km/h {16.8 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 main switch: OFF
  – Cruise control related DTCs (P0564, P0571) 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
  – Neutral switch or CPP 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 RESUME/ACCEL switch is on.

### Cruise control function

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

Function list

Function | Contents
--- | ---
Accelerating | • When any of the following conditions are met while driving in cruise control and when the RESUME/ACCEL switch is continuously pressed, the PCM gradually increases the set vehicle speed. – Except during resume operation – The RESUME/ACCEL switch is on one time or more during resume operation.
Coasting | • When the SET/COAST switch is continuously pressed, the PCM gradually decreases the set vehicle speed.
Resume | • When the RESUME/ACCEL 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 mph} and controls the throttle valve actuator. – During cruise control – RESUME/ACCEL switch off – The RESUME/ACCEL switch switches from off to on – When actual vehicle speed is lower (set vehicle speed -2 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 mph} and controls the throttle valve actuator so that the vehicle speed is close to the set vehicle speed. – During cruise control – The RESUME/ACCEL switch switches from off to on

## Vehicle Speed Limiter (Except for European (L.H.D. U.K.) specs.)

• When the actual vehicle speed exceeds the set vehicle speed, the vehicle speed limiter controls the throttle valve actuator so that vehicle speed is maintained at the set vehicle speed or less. It also reduces shock when the vehicle speed reaches the set vehicle speed and prevents rapid temperature increase of the catalytic converter during high speed.

• Set vehicle speed is as follows:

  – 18-inch tire: 231 km/h {143.5 mph}
  – 16-inch tire: 211 km/h {131.1 mph}