Mazda CX-5 Service & Repair Manual: Drive By Wire Control

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

• 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.

Engine oil temperature control

• If the PCM determines that the engine oil temperature is too high, the throttle valve opening angle is decreased and the engine speed is reduced.

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..

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 (ATX)

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

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

• If the increase in vehicle speed on the down slope is high, the PCM sends a down shift signal to the TCM (ATX).

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

• Shift position: neutral (MTX)

• Selector lever position: N position (ATX)

• 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.

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

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

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

• 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.