Infiniti Q45. Manual - part 347

ENGINE CONTROL SYSTEM

EC-27

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During acceleration

The knock sensor retard system is designed only for emergencies. The basic ignition timing is programmed
within the anti-knocking zone, if recommended fuel is used under dry conditions. The retard system does not
operate under normal driving conditions. If engine knocking occurs, the knock sensor monitors the condition.
The signal is transmitted to the ECM. The ECM retards the ignition timing to eliminate the knocking condition.

Fuel Cut Control (at No Load and High Engine Speed)

NBS001Q7

INPUT/OUTPUT SIGNAL CHART

*: This signal is sent to the ECM through CAN communication line.

SYSTEM DESCRIPTION

If the engine speed is above 1,400 rpm under no load (for example, the selector lever position is neutral and
engine speed is over 1,400 rpm) fuel will be cut off after some time. The exact time when the fuel is cut off var-
ies based on engine speed.
Fuel cut will be operated until the engine speed reaches 1,000 rpm, then fuel cut will be cancelled.

NOTE:
This function is different from deceleration control listed under Multiport Fuel Injection (MFI) System,

EC-24

Sensor

Input Signal to ECM

ECM function

Actuator

Park/neutral position (PNP) switch

Neutral position

Fuel cut con-
trol

Fuel injector

Accelerator pedal position sensor

Accelerator pedal position

Engine coolant temperature sensor

Engine coolant temperature

Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)

Engine speed

Wheel sensor

Vehicle speed*

EC-28

AIR CONDITIONING CUT CONTROL

PFP:23710

Input/Output Signal Chart

NBS001Q8

*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.

System Description

NBS001Q9

This system improves engine operation when the air conditioner is used.
Under the following conditions, the air conditioner is turned off.

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When the accelerator pedal is fully depressed.

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When cranking the engine.

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At high engine speeds.

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When the engine coolant temperature becomes excessively high.

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When operating power steering during low engine speed or low vehicle speed.

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When engine speed is excessively low.

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When refrigerant pressure is excessively low or high.

Sensor

Input Signal to ECM

ECM function

Actuator

Air conditioner switch

Air conditioner ON signal

Air conditioner
cut control

Air conditioner relay

Accelerator pedal position sensor

Accelerator pedal position

Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)

Engine speed*

Engine coolant temperature sensor

Engine coolant temperature

Battery

Battery voltage*

Refrigerant pressure sensor

Refrigerant pressure

Power steering pressure sensor

Power steering operation

Wheel sensor

Vehicle speed*

AUTOMATIC SPEED CONTROL DEVICE (ASCD)

EC-29

AUTOMATIC SPEED CONTROL DEVICE (ASCD)

PFP:18930

System Description

NBS001QA

INPUT/OUTPUT SIGNAL CHART

*: This signal is sent to the ECM through CAN communication line

BASIC ASCD SYSTEM

Refer to Owner's Manual for ASCD operating instructions.
Automatic Speed Control Device (ASCD) allows a driver to keep vehicle at predetermined constant speed
without depressing accelerator pedal. Driver can set vehicle speed in advance between approximately 40 km/
h (25 MPH) and 144 km/h (89 MPH).
ECM controls throttle angle of electric throttle control actuator to regulate engine speed.
Operation status of ASCD is indicated by CRUISE lamp and SET lamp in combination meter. If any malfunc-
tion occurs in ASCD system, it automatically deactivates control.
NOTE:
Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws.

SET OPERATION

Press MAIN switch. (The CRUISE lamp in combination meter illuminates.)
When vehicle speed reaches a desired speed between approximately 40 km/h (25 MPH) and 144 km/h (89
MPH), press SET/COAST switch. (Then SET lamp in combination meter illuminates.)

ACCELERATE OPERATION

If the RESUME/ACCELERATE switch is pressed during cruise control driving, increase the vehicle speed until
the switch is released or vehicle speed reaches maximum speed controlled by the system.
And then ASCD will keep the new set speed.

CANCEL OPERATION

When any of following conditions exist, cruise operation will be canceled.

●

CANCEL switch is pressed

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More than 2 switches at ASCD steering switch are pressed at the same time (Set speed will be cleared)

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Brake pedal is depressed

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Selector lever is changed to N, P, R position

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Vehicle speed decreased to 13 km/h (8 MPH) lower than the set speed

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TCS system is operated

When the ECM detects any of the following conditions, the ECM will cancel the cruise operation and inform
the driver by blinking indicator lamp.

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Engine coolant temperature is slightly higher than the normal operating temperature, CRUISE lamp may
blink slowly.
When the engine coolant temperature decreases to the normal operating temperature, CRUISE lamp will
stop blinking and the cruise operation will be able to work by pressing SET/COAST switch or RESUME/
ACCELERATE switch.

●

Malfunction for some self-diagnoses regarding ASCD control: SET lamp will blink quickly.

If MAIN switch is turned to OFF during ASCD is activated, all of ASCD operations will be canceled and vehicle
speed memory will be erased.

Sensor

Input signal to ECM

ECM function

Actuator

ASCD brake switch

Brake pedal operation

ASCD vehicle speed control

Electric throttle control
actuator

Stop lamp switch

Brake pedal operation

ASCD steering switch

ASCD steering switch operation

Park/Neutral position (PNP)
switch

Gear position

Wheel sensor

Vehicle speed*

TCM

Powertrain revolution*

EC-30

AUTOMATIC SPEED CONTROL DEVICE (ASCD)

COAST OPERATION

When the SET/COAST switch is pressed during cruise control driving, decrease vehicle set speed until the
switch is released. And then ASCD will keep the new set speed.

RESUME OPERATION

When the RESUME/ACCELERATE switch is pressed after cancel operation other than pressing MAIN switch
is performed, vehicle speed will return to last set speed. To resume vehicle set speed, vehicle condition must
meet following conditions.

●

Brake pedal is released

●

A/T selector lever is in other than P and N positions

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Vehicle speed is greater than 40 km/h (25 MPH) and less than 144 km/h (89 MPH)

Component Description

NBS001QB

ASCD STEERING SWITCH

Refer to

EC-586

ASCD BRAKE SWITCH