Nissan Quest E52. Manual - part 454

EC-26

< SYSTEM DESCRIPTION >

[VQ35DE]

COMPONENT PARTS

This sensor is a potentiometer which transforms the power steering load into output voltage, and emits the
voltage signal to the ECM. The ECM controls the electric throttle control actuator and adjusts the throttle valve
opening angle to increase the engine speed and adjusts the idle speed for the increased load.

Cooling Fan

INFOID:0000000009650940

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].
Refer to

EC-45, "COOLING FAN CONTROL : System Description"

for cooling fan operation.

COOLING FAN MOTOR RELAY

Power supply for the cooling fan motor is provided via cooling fan motor relay.

EVAP Canister

INFOID:0000000009650941

The fuel vapor in the sealed fuel tank is led into the EVAP canister which contains activated carbon and the
vapor is stored there when the engine is not operating or when refueling to the fuel tank.
For details, refer to

EC-49, "EVAPORATIVE EMISSION SYSTEM : System Description"

EVAP Canister Purge Volume Control Solenoid Valve

INFOID:0000000009650942

The EVAP canister purge volume control solenoid valve is used to
control the flow rate of fuel vapor from the EVAP canister. The EVAP
canister purge volume control solenoid valve is moved by ON/OFF
pulses from the ECM. The longer the ON pulse, the greater the
amount of fuel vapor that will flow through the valve.

EVAP Canister Vent Control Valve

INFOID:0000000009650943

The EVAP canister vent control valve is located on the EVAP canis-
ter and is used to seal the canister vent.
This solenoid valve responds to signals from the ECM. When the
ECM sends an ON signal, the coil in the solenoid valve is energized.
A plunger will then move to seal the canister vent. The ability to seal
the vent is necessary for the on board diagnosis of other evaporative
emission control system components.
This solenoid valve is used only for diagnosis, and usually remains
opened.
When the vent is closed, under normal purge conditions, the evapo-
rative emission control system is depressurized and allows “EVAP
Control System” diagnosis.

EVAP Control System Pressure Sensor

INFOID:0000000009650944

The EVAP control system pressure sensor detects pressure in the
purge line. The sensor output voltage to the ECM increases as pres-
sure increases.

PBIB3489E

JSBIA1337GB

PBIB3370E

COMPONENT PARTS

EC-27

< SYSTEM DESCRIPTION >

[VQ35DE]

Air Fuel Ratio (A/F) Sensor 1

INFOID:0000000009650945

DESCRIPTION

The air fuel ratio (A/F) sensor 1 is a planar one-cell limit current sen-
sor. The sensor element of the A/F sensor 1 is composed an elec-
trode layer, which transports ions. It has a heater in the element.
The sensor is capable of precise measurement = 1, but also in the
lean and rich range. Together with its control electronics, the sensor
outputs a clear, continuous signal throughout a wide range.
The exhaust gas components diffuse through the diffusion layer at
the sensor cell. An electrode layer is applied voltage, and this current
relative oxygen density in lean. Also this current relative hydrocar-
bon density in rich.

Therefore, the A/F sensor 1 is able to indicate air fuel ratio by this
electrode layer of current. In addition, a heater is integrated in the
sensor to ensure the required operating temperature of approxi-
mately 800

C (1,472

F).

A/F SENSOR 1 HEATER

A/F sensor 1 heater is integrated in the sensor.
The ECM performs ON/OFF duty control of the A/F sensor 1 heater corresponding to the engine operating
condition to keep the temperature of A/F sensor 1 element within the specified range.

Heated Oxygen Sensor 2

INFOID:0000000009650946

DESCRIPTION

The heated oxygen sensor 2, after three way catalyst (manifold),
monitors the oxygen level in the exhaust gas.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1
are shifted, the air fuel ratio is controlled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1 V in richer conditions to 0 V in leaner con-
ditions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.

HEATED OXYGEN SENSOR 2 HEATER

Heated oxygen sensor 2 heater is integrated in the sensor.
The ECM performs ON/OFF control of the heated oxygen sensor 2 heater corresponding to the engine speed,
amount of intake air and engine coolant temperature.

JMBIA0112GB

JPBIA5446GB

SEF327R

Engine speed

Heated oxygen sensor 2 heater

Above 3,600 rpm

OFF

Below 3,600 rpm after the following conditions are met.
• Engine: After warming up
• Keeping the engine speed between 3,500 and 4,000 rpm for 1

minute and at idle for 1 minute under no load

EC-28

< SYSTEM DESCRIPTION >

[VQ35DE]

COMPONENT PARTS

Fuel Level Sensor Unit and Fuel Pump

INFOID:0000000009650948

FUEL PUMP

The ECM activates the fuel pump for 1 second after the ignition
switch is turned ON to improve engine start ability. If the ECM
receives a engine speed signal from the camshaft position sensor
(PHASE), it knows that the engine is rotating, and causes the pump
to operate. If the engine speed signal is not received when the igni-
tion switch is ON, the engine stalls. The ECM stops pump operation
and prevents battery discharging, thereby improving safety. The
ECM does not directly drive the fuel pump. It controls the ON/OFF
fuel pump relay, which in turn controls the fuel pump.

FUEL LEVEL SENSOR

The fuel level sensor is mounted in the fuel level sensor unit.
The sensor detects a fuel level in the fuel tank and transmits a signal to the combination meter. The combina-
tion meter sends the fuel level sensor signal to the ECM via the CAN communication line.
It consists of two parts, one is mechanical float and the other is variable resistor. Fuel level sensor output volt-
age changes depending on the movement of the fuel mechanical float.

Fuel Tank Temperature Sensor

INFOID:0000000009650949

The fuel tank temperature sensor is used to detect the fuel tempera-
ture inside the fuel tank. The sensor modifies a voltage signal from
the ECM. The modified signal returns to the ECM as the fuel temper-
ature input. The sensor uses a thermistor which is sensitive to the
change in temperature. The electrical resistance of the thermistor
decreases as temperature increases.
<Reference data>

*: These data are reference values and are measured between ECM terminals 95 (Fuel tank temperature sensor) and ground.

ASCD Steering Switch

INFOID:0000000009650950

ASCD steering switch has variant values of electrical resistance for each button. ECM reads voltage variation
of switch, and determines which button is operated.
Refer to

EC-44, "AUTOMATIC SPEED CONTROL DEVICE (ASCD) : System Description"

for the ASCD func-

tion.

Stop Lamp Switch & ASCD Brake Switch

INFOID:0000000009650951

Stop lamp switch and ASCD brake switch are installed to brake pedal bracket.
ECM detects the state of the brake pedal by those two types of input (ON/OFF signal).

JSBIA1282ZZ

Condition

Fuel pump operation

Ignition switch is turned to ON.

Operates for 1 second.

Engine running and cranking

Operates.

When engine is stopped

Stops in 1.5 seconds.

Except as shown above

Stops.

Fluid temperature

[

C (

F)]

Voltage*

(V)

Resistance

Ω

)

20 (68)

3.5

2.3 - 2.7

50 (122)

2.2

0.79 - 0.90

SEF012P

COMPONENT PARTS

EC-29

< SYSTEM DESCRIPTION >

[VQ35DE]

Brake pedal

ASCD brake switch

Stop lamp switch

Released

OFF

Depressed

OFF

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