Nissan Pathfinder. Manual — part 430
EC-26
< SYSTEM DESCRIPTION >
[VQ35DE]
COMPONENT PARTS
Knock Sensor
INFOID:0000000009178025
The knock sensor is attached to the cylinder block. It senses engine
knocking using a piezoelectric element. A knocking vibration from
the cylinder block is sensed as vibrational pressure. This pressure is
converted into a voltage signal and sent to the ECM.
Malfunction Indicator Lamp (MIL)
INFOID:0000000009178026
Malfunction Indicator lamp (MIL) is located on the combination
meter.
MIL will illuminate when the ignition switch is turned ON without the
engine running. This is a bulb check.
When the engine is started, MIL should turn OFF. If the MIL remains
illuminated, the on board diagnostic system has detected an engine
system malfunction.
For details, refer to
EC-58, "DIAGNOSIS DESCRIPTION : Malfunc-
.
Mass Air Flow Sensor (With Intake Air Temperature Sensor)
INFOID:0000000009178027
MASS AIR FLOW SENSOR
The mass air flow sensor is placed in the stream of intake air. It
measures the intake flow rate by measuring a part of the entire
intake flow. The mass air flow sensor controls the temperature of the
hot wire to a certain amount. The heat generated by the hot wire is
reduced as the intake air flows around it. The more air, the greater
the heat loss.
Therefore, the electric current supplied to hot wire is changed to
maintain the temperature of the hot wire as air flow increases. The
ECM detects the air flow by means of this current change.
INTAKE AIR TEMPERATURE SENSOR
The intake air temperature sensor is built-into mass air flow sensor. The sensor detects intake air temperature
and transmits a signal to the ECM.
The temperature sensing unit uses a thermistor which is sensitive to the change in temperature. Electrical
resistance of the thermistor decreases in response to the temperature rise.
<Reference data>
*: These data are reference values and are measured between ECM terminals.
JSBIA0284ZZ
JSBIA1315ZZ
PBIA9559J
Intake air temperature
[
°C (°F)]
Voltage
*
(V)
Resistance (k
Ω)
25 (77)
3.3
1.800 - 2.200
80 (176)
1.2
0.283 - 0.359
SEF012P
COMPONENT PARTS
EC-27
< SYSTEM DESCRIPTION >
[VQ35DE]
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Oil Pressure Warning Lamp
INFOID:0000000009178028
Oil pressure warning lamp is located on the combination meter.
It indicates the low pressure of the engine oil and the malfunction of
the engine oil pressure system.
Combination meter turns the oil pressure warning lamp ON/OFF
according to the oil pressure warning lamp signal received from
ECM via CAN communication.
For details, refer to
EC-43, "ENGINE PROTECTION CONTROL AT
LOW ENGINE OIL PRESSURE : System Description"
Power Valve Actuator 1 and 2
INFOID:0000000009178029
The power valves are used to control the suction passage of the variable induction air control system. They
are set in the fully closed or fully opened position by the power valve actuators operated by the vacuum stored
in the vacuum tank. The vacuum to power valve actuators is controlled by the VIAS control solenoid valves.
Refrigerant Pressure Sensor
INFOID:0000000009178030
The refrigerant pressure sensor is installed at the condenser of the air conditioner system. The sensor uses an
electrostatic volume pressure transducer to convert refrigerant pressure to voltage. The voltage signal is sent
to ECM, and ECM controls cooling fan system.
Stop Lamp Switch & Brake Pedal Position Switch
INFOID:0000000009178031
Stop lamp switch and brake pedal position switch are installed to brake pedal bracket.
ECM detects the state of the brake pedal by those two types of input (ON/OFF signal).
VIAS Control Solenoid Valve 1 and 2
INFOID:0000000009178032
The VIAS control solenoid valve cuts the intake manifold vacuum signal for power valve control. It responds to
ON/OFF signals from the ECM. When the solenoid is OFF, the vacuum signal from the intake manifold is cut.
When the ECM sends an ON signal the coil pulls the plunger downward and sends the vacuum signal to the
power valve actuator.
PBIA8559J
PBIB2657E
Brake pedal
Brake pedal position switch
Stop lamp switch
Released
ON
OFF
Depressed
OFF
ON
EC-28
< SYSTEM DESCRIPTION >
[VQ35DE]
STRUCTURE AND OPERATION
STRUCTURE AND OPERATION
Positive Crankcase Ventilation (PCV)
INFOID:0000000009178033
This system returns blow-by gas to the intake manifold.
The positive crankcase ventilation (PCV) valve is provided to conduct crankcase blow-by gas to the intake
manifold.
During partial throttle operation of the engine, the intake manifold sucks the blow-by gas through the PCV
valve.
Normally, the capacity of the valve is sufficient to handle any blow-by and a small amount of ventilating air.
The ventilating air is drawn from the air inlet tubes into the crankcase. In this process the air passes through
the hose connecting air inlet tubes to rocker cover.
Under full-throttle condition, the manifold vacuum is insufficient to draw the blow-by flow through the valve.
The flow goes through the hose connection in the reverse direction.
On vehicles with an excessively high blow-by, the valve does not
meet the requirement. This is because some of the flow will go
through the hose connection to the air inlet tubes under all condi-
tions.
SEC921C
PBIB1588E
STRUCTURE AND OPERATION
EC-29
< SYSTEM DESCRIPTION >
[VQ35DE]
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On Board Refueling Vapor Recovery (ORVR)
INFOID:0000000009178034
From the beginning of refueling, the air and vapor inside the fuel tank go through refueling EVAP vapor cut
valve and EVAP/ORVR line to the EVAP canister. The vapor is absorbed by the EVAP canister and the air is
released to the atmosphere.
When the refueling has reached the full level of the fuel tank, the refueling EVAP vapor cut valve is closed and
refueling is stopped because of auto shut-off. The vapor which was absorbed by the EVAP canister is purged
during driving.
WARNING:
When conducting inspections below, be sure to observe the following:
• Put a “CAUTION: FLAMMABLE” sign in workshop.
• Never smoke while servicing fuel system. Keep open flames and sparks away from work area.
• Always to furnish the workshop with a CO
2
fire extinguisher.
CAUTION:
• Before removing fuel line parts, carry out the following procedures:
- Put drained fuel in an explosion-proof container and put lid on securely.
- Release fuel pressure from fuel line. Refer to
.
- Disconnect battery ground cable.
• Always replace O-ring when the fuel gauge retainer is removed.
• Never kink or twist hose and tube when they are installed.
• Never tighten hose and clamps excessively to avoid damaging hoses.
• After installation, run engine and check for fuel leakage at connections.
• Never attempt to top off the fuel tank after the fuel pump nozzle shuts off automatically.
Continued refueling may cause fuel overflow, resulting in fuel spray and possibly a fire.
PBIB1068E
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