EC-570
< SYSTEM DESCRIPTION >[VQ35DE]
SYSTEM
MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system prov
ides the best air-fuel mixture ratio for drive ability and emission control.
The three way catalyst (manifold) can better reduce CO , HC and NOx emissions. This system uses A/F sen-
sor 1 in the exhaust manifold to monitor whether the engine operation is rich or lean. The ECM adjusts the
injection pulse width according to the sensor voltage signal. For more information about A/F sensor 1, refer to
EC-552, "Air Fuel Ratio (A/F) Sensor 1"
. This maintains the mixture ratio within the range of stoichiometric
(ideal air-fuel mixture).
This stage is referred to as the closed loop control condition.
Heated oxygen sensor 2 is located downstream of the th ree way catalyst (manifold). Even if the switching
characteristics of A/F sensor 1 shift, the air-fuel ratio is controlled to stoichiometric by the signal from heated
oxygen sensor 2.
• Open Loop Control
The open loop system condition refers to when the ECM detects any of the following conditions. Feedback
control stops in order to maintain stabilized fuel combustion.
- Deceleration and acceleration
- High-load, high-speed operation
- Malfunction of A/F sensor 1 or its circuit
- Insufficient activation of A/F sensor 1 at low engine coolant temperature
- High engine coolant temperature
- During warm-up
- After shifting from N to D
- When starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors t he mixture ratio signal transmitted from A/F sensor 1.
This feedback signal is then sent to the ECM. The ECM c ontrols the basic mixture ratio as close to the theoret-
ical mixture ratio as possible. However, the basic mi xture ratio is not necessarily controlled as originally
designed. Both manufacturing differences (i.e., mass ai r flow sensor hot wire) and characteristic changes dur-
ing operation (i.e., fuel injector clogging) directly affect mixture ratio.
Accordingly, the difference between the basic and theoretical mixture ratios is monitored in this system. This is
then computed in terms of “injection pulse duration” to automatically compensate for the difference between
the two ratios.
“Fuel trim” refers to the feedback compensation value co mpared against the basic injection duration. Fuel trim
includes “short-term fuel trim” and “long-term fuel trim”.
“Short-term fuel trim” is the short-term fuel compensati on used to maintain the mixture ratio at its theoretical
value. The signal from A/F sensor 1 indicates whether the mixture ratio is RICH or LEAN compared to the the-
oretical value. The signal then triggers a reduction in fuel volume if the mixture ratio is rich, and an increase in
fuel volume if it is lean.
“Long-term fuel trim” is overall fuel compensation carri ed out over time to compensate for continual deviation
of the “short-term fuel trim” from the central value. Continual deviation will occur due to individual engine differ-
ences, wear over time and changes in the usage environment.
PBIB3020E
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM
EC-572
< SYSTEM DESCRIPTION >[VQ35DE]
SYSTEM
*: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
Ignition order: 1 - 2 - 3 - 4 - 5 - 6
The ignition timing is controlled by the ECM to maintain the best air-fuel ratio for every running condition of the
engine. The ignition timing data is stored in the ECM.
The ECM receives information such as the injection pulse width and camshaft position sensor (PHASE) sig-
nal. Computing this information, ignition si gnals are transmitted to the power transistor.
During the following conditions, the ignition timing is re vised by the ECM according to the other data stored in
the ECM.
• At starting
• During warm-up
• At idle
• At low battery voltage
• 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.
AIR CONDITIONING CUT CONTROL
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS) Engine speed
*
Ignition timing
control Ignition coil
(with power transistor)
Camshaft position sensor
(PHASE) Piston position
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Transmission range switch Gear position
Battery Battery voltage
*
Knock sensor Engine knocking
Combination meter Vehicle speed CAN communi-
cation
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM
SYSTEMEC-573
< SYSTEM DESCRIPTION > [VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
NP
O
AIR CONDITIONING CUT CONTROL : System DescriptionINFOID:0000000009462517
SYSTEM DIAGRAM
*1: Automatic air conditioning system
*2: Manual air conditioning system
INPUT/OUTPUT SIGNAL CHART
*1: ECM determines the start signal status by the signals of engine speed and battery voltage.
*2: Automatic air conditioning system
*3: Manual air conditioning system
SYSTEM DESCRIPTION
This system improves engine operation when the air conditioner is used.
Under the following conditions, the air conditioner is turned OFF.
• When the accelerator pedal is fully depressed.
• When cranking the engine.
• At high engine speeds.
• When the engine coolant temperature becomes excessively high.
• When operating power steering during low engine speed or low vehicle speed.
JSBIA2685GB
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS) Engine speed
*1
Air conditioner
cut control IPDM E/R
↓
Air conditioner relay
↓
Compressor
Camshaft position sensor (PHASE)
Engine coolant temperature sensor Engine coolant temperature
Accelerator pedal position sensor Accelerator pedal position
Battery Battery voltage*1
Refrigerant pressure sensor Refrigerant pressure
Power steering control module EPS operation signal
CAN communi-
cation line
Combination meter Vehicle speed signal
A/C auto amp.
*2• A/C ON signal
• Blower fan ON signal
BCM
*3
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM
SYSTEMEC-575
< SYSTEM DESCRIPTION > [VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
NP
O
• More than 2 switches at ASCD steer
ing switch are pressed at the same time (Set speed will be cleared)
• Brake pedal is depressed
• Selector lever is in the N, P, R position
• Vehicle speed decreased to 13 km/h (8 MPH) lower than the set speed
• 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.
• Engine coolant temperature is slightly higher than the normal operating temperature, CRUISE lamp may
blink slowly.
When the engine coolant temperature decreases to t he 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 indicator will blink quickly.
If MAIN switch is turned to OFF while ASCD is acti vated, all of ASCD operations will be canceled and vehicle
speed memory will be erased.
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 maintain the new set speed.
RESUME OPERATION
When the RESUME/ACCELERATE switch is pressed afte r cancel operation other than pressing MAIN switch
is performed, vehicle speed will return to last set s peed. To resume vehicle set speed, vehicle condition must
meet following conditions.
• Brake pedal is released
• A/T selector lever is in the P and N positions
• Vehicle speed is greater than 40 km/h (25 MPH) and less than 144 km/h (89 MPH)
COOLING FAN CONTROL
COOLING FAN CONTROL : System DescriptionINFOID:0000000009462519
SYSTEM DIAGRAM
Automatic Air Conditioning System
JSBIA1589GB
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM
EC-576
< SYSTEM DESCRIPTION >[VQ35DE]
SYSTEM
Manual Air Conditioning System
INPUT/OUTPUT SIGNAL CHART
*1: The ECM determines the start signal status by the signals of engine speed and battery voltage.
*2: This signal is sent to ECM via the CAN communication line.
*3: Automatic air conditioning system
*4: Manual air conditioning system
SYSTEM DESCRIPTION
The ECM controls the cooling fan corresponding to the vehicle speed, engine coolant temperature, refrigerant
pressure, and air conditioner ON signal. The control system has 4-step control [HIGH/MIDDLE/LOW/OFF].
JSBIA0321GB
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE) Engine speed*
1
Piston position
Cooling fan
control IPDM E/R
↓
Cooling fan relay
↓
Cooling fan motor
Engine coolant temperature sensor Engine coolant temperature
Refrigerant pressure sensor Refrigerant pressure
Battery Battery voltage*
1
Combination meter
Vehicle speed signal*2
A/C auto amp.*3• A/C ON signal
• Blower fan ON signal
BCM
*4
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM
EC-580
< SYSTEM DESCRIPTION >[VQ35DE]
SYSTEM
EVAPORATIVE EMISSION SYSTEM : System Description
INFOID:0000000009462521
SYSTEM DIAGRAM
INPUT/OUTPUT SIGNAL CHART
*1: ECM determines the start signal status by the signals of engine speed and battery voltage.
*2: This signal is sent to the ECM via the CAN communication line.
JSBIA0371GB
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS) Engine speed*
1
Piston position
EVAP canister
purge flow control EVAP canister purge vol-
ume control solenoid valve
Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Air fuel ratio (A/F) sensor 1 Density of oxygen in exhaust gas
(Mixture ratio fe edback signal)
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Battery Battery voltage*
1
Fuel tank temperature sensor Fuel temperature in fuel tank
EVAP control system pressure sensor Pressure in purge line
Combination meter Vehicle speed*
2
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM
EC-582
< SYSTEM DESCRIPTION >[VQ35DE]
SYSTEM
Manual Air Conditioning System
INPUT/OUTPUT SIGNAL CHART
*1: ECM determines the start signal status
by the signals of engine speed and battery voltage.
*2: Automatic air conditioning system
*3: Manual air conditioning system
SYSTEM DESCRIPTION
ECM calculates the value of signal transmitted from t he accelerator pedal and activates the throttle valve by
transmitting a control signal to the electric throttle c ontrol actuator. This allows the optimum throttle angle and
improves drivability and fuel consumption. In addition, ECM learns the fully closed position every time when
the ignition switch is turned OFF to improv e the accuracy in throttle valve position.
When a malfunction occurs in the throttle control system , the throttle valve is closed by the return spring and
maintains the minimum engine speed by holding a slightly opened condition which is close to the fully opened
condition. This allows the securing of brake syste m, power steering system, and electric system and the
ensuring of the safety.
INTAKE VALVE TIMING CONTROL
JSBIA1917GB
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS) Engine speed
*1
Throttle controlElectric throttle control
actuator
Engine coolant temperature sensor Engine coolant temperature
Mass air flow sensor Amount of intake air
Intake air temperature sensor Intake air temperature
Accelerator pedal position sensor Accelerator pedal position
Ignition switch Start signal and ignition OFF
Combination meter CAN communi-
cation Vehicle speed signal
A/C auto amp.
*2CAN communi-
cation • A/C ON signal
• Blower fan ON signal
BCM
*3
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM
SYSTEMEC-583
< SYSTEM DESCRIPTION > [VQ35DE]
C
D E
F
G H
I
J
K L
M A
EC
NP
O
INTAKE VALVE TIMING CONT
ROL : System DescriptionINFOID:0000000009462523
SYSTEM DIAGRAM
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM via the CAN communication line
SYSTEM DESCRIPTION
This mechanism hydraulically controls cam phases c ontinuously with the fixed operating angle of the intake
valve.
The ECM receives signals such as crankshaft posit ion, camshaft position, engine speed, and engine coolant
temperature. Then, the ECM sends ON/OFF pulse duty si gnals to the intake valve timing (IVT) control sole-
noid valve depending on driving status. This makes it po ssible to control the shut/open timing of the intake
valve to increase engine torque in low/mid speed range and output in high-speed range.
ENGINE PROTECTION CONTROL AT LOW ENGINE OIL PRESSURE
ENGINE PROTECTION CONTROL AT LOW ENGINE OIL PRESSURE : System De-
JPBIA4760GB
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS) Engine speed and piston position
Intake valve
timing control Intake valve timing control
solenoid valve
Camshaft position sensor (PHASE)
Engine oil temperature sensor Engine oil temperature
Engine coolant temperature sensor Engine coolant temperature
Combination meter Vehicle speed signal*
JMBIA0060GB
Revision: November 20132014 Altima NAMRevision: November 20132014 Altima NAM