Denso HP4
Denso HP4
Denso HP4
4 HP4 Type
(1) Construction and Characteristics
• The HP4 basic supply pump construction is the same as for the HP3. The composition is also the same as the
HP3,being made up of the pump unit (eccentric cam, ring cam, plunger), the SCV (suction control valve), the fuel
temperature sensor, and the feed pump. The main difference is that there are three plungers.
• Because there are three plungers, they are positioned at intervals of 120? around the outside of the ring cam. In
ad-dition, the fuel delivery capacity is 1.5 times that of the HP3.
• The fuel discharge quantity is controlled by the SCV, the same as for the HP3.
Delivery Valve
Feed Pump
Plunger
Suction Valve
Eccentric Cam
Q000850E
(2) Exploded View
Plunger
Camshaft
Eccentric Cam
Ring Cam
Q000851E
• Because the rotation of the camshaft makes the eccentric cam rotate eccentrically, the ring cam follows this and
thismoves the three plungers reciprocally. (The ring cam itself does not rotate.)
(4) Supply Pump Operation
Supply Pump Overall Fuel Flow
• The fuel is suctioned by the feed pump from the fuel tank and sent to the SCV. At this time, the regulating valve
adjusts the fuel pressure to below a certain level. The fuel sent from the feed pump has the required discharge
quantity adjusted by the SCV, and enters the pump unit through the suction valve. The fuel pumped by the pump
unit is pumped through the delivery valve to the rail.
Feed Pump from Fuel Tank (Suction)
SCV from Feed Pump (Low Pressure)
Pump Unit from SCV (Low-Pressure Adjustment Complete)
From Pump Unit to Rail (High Pressure)
SCV Camshaft
To Rail
From Fuel
Tank Feed Pump
Ring Cam
Plunger
Delivery Valve Suction Valve
Q000853E
Operation
• The discharge quantity is controlled by the SCV. As with the HP3, the valve opening is adjusted by duty ratio
control. The only difference from the HP3 is the shape of the pump unit. Operation and control are basically the
same. For details on operation and control, see the explanation of the HP3.
4. RAIL DESCCRIPTION
Pressure Limiter
Rail
Q000854E
Rail Stores pressurized fuel that has been pumped from the supply pump and
distributes the fuel to each cylinder injector.
Pressure Limiter Opens the valve to release pressure if the pressure in the rail becomes
abnormally high.
Rail Pressure Sensor (Pc Sensor) Detects the fuel pressure in the rail.
Flow Damper Reduces the pressure pulsations of fuel in the rail. If fuel flows out excessively,
the damper closes the fuel passage to prevent further flow of fuel. Mostly used
with engines for large vehicles.
Pressure Discharge Valve Controls the fuel pressure in the rail. Mostly used with engines for passenger cars.
(1) Pressure Limiter
• The pressure limiter opens to release the pressure if abnormally high pressure is generated. If pressure within the
rail becomes abnormally high, the pressure limiter operates (opens). It resumes operation (closes) after the
pressure falls to a certain level. Fuel released by the pressure limiter returns to the fuel tank.
The operating pressures for the pressure limiter depend on the vehicle model and are approximately 140-230MPa for
the valve opening pressure, and approximately 30-50MPa for the valve closing pressure.
Leak
(To Fuel Tank )
Pressure Limiter
Valve Close
Return
Vout
Pc ECU
GND
GND Vout Vcc
Rail Pressure
Q000856E
• There are also rail pressure sensors that have dual systems to provide a backup in case of breakdown. The
outputvoltage is offset.
Output Voltage 2
PR ECU
Pc PR2 ECU
Sensors
E2
E2S
VC PR E2 Rail Pressure
Q000857E
Spring Seat
Q000859E
(1) X1 Type
• Precision control is attained through electronic control of the injection. The TWV comprises two valves: the inner
valve (fixed) and the outer valve (movable).
(2) X2 Type
• By reducing the injector actuation load, the injector has been made more compact and energy efficient, and its
injection precision has been improved. The TWV directly opens and closes the outlet orifice.
(3) G2 Type
• To ensure high pressure, the G2 type has improved pressure strength, sealing performance and pressure wear
resistance. It also has improved high-speed operability, enabling higher-precision injection control and multi-
injection.
< NOTE >
Multi-injection means that for the purpose of reducing exhaust gas emissions and noise, the main injection is
accomplished with one to five injections of fuel without changing the injection quantity.
Main Injection
Time
Q000866E
5.3 Injector Operation
z The injector controls injection through the fuel pressure in the control chamber. The TWV executes leak control of
the fuel in the control chamber to control the fuel pressure within the control chamber. The TWV varies with the
injector type.
Non-Injection
• When the TWV is not energized, the TWV shuts off the leak passage from the control chamber, so the fuel pressure
in the control chamber and the fuel pressure applied to the nozzle needle are both the same rail pressure. The
nozzle needle thus closes due to the difference between the pressure-bearing surface area of the command piston
and the force of the nozzle spring, and fuel is not injected. For the X1 type, the leak passage from the control
chamber is shut off by the outer valve being pressed against the seat by the force of the spring, and the fuel
pressure within the outer valve. For the X2/G2 types, the control chamber outlet orifice is closed directly by the
force of the spring.
Injection
• When TWV energization starts, the TWV valve is pulled up, opening the leak passage from the control chamber.
When this leak passage opens, the fuel in the control chamber leaks out and the pressure drops. Because of the
drop in pressure within the control chamber, the pressure on the nozzle needle overcomes the force pressing
down, the nozzle needle is pushed up, and injection starts. When fuel leaks from the control chamber, the flow
quantity is restricted by the orifice, so the nozzle opens gradually. The injection rate rises as the nozzle opens. As
current continues to be applied to the TWV, the nozzle needle eventually reaches the maximum amount of lift,
which results in the maximum injection rate. Excess fuel is returned to the fuel tank through the path shown.
End of Injection
• When TWV energization ends, the valve descends, closing the leak passage from the control chamber. When the
leak passage closes, the fuel pressure within the control chamber instantly returns to the rail pressure, the nozzle
closes suddenly, and injection stops.
5.4 Injector Actuation Circuit
z In order to improve injector responsiveness, the actuation voltage has been changed to high voltage, speeding up
both solenoid magnetization and the response of the TWV. The EDU or the charge circuit in the ECU raises the
respective battery voltage to approximately 110V, which is supplied to the injector by signal from the ECU to actuate
the injector.
5.5 Other Injector Component Parts
(1) Hollow Screw with Damper
• The hollow screw with damper enhances injection quantity accuracy, by reducing the back-pressure pulsations
(pressure fluctuations) of the leak fuel. In addition, it minimizes the back-pressure dependence (the effect of the
pressure in the leak pipe changing the injection quantity even though the injection command is the same) of the
fuel in the leak pipe.
QR codes are a new two-dimensional code that was developed by DENSO. In addition to injection quantity correction
data, the code contains the part number and the product number, which can be read at extremely high speeds.
Handling Injectors with QR Codes (Reference)
- Injectors with QR codes have the engine ECU recognize and correct the injectors, so when an injector or the
engine ECU is replaced, it is necessary to register the injector's ID code in the engine ECU.
Spare Injector
Engine ECU
QD1536E
Q000985E
Actuation Circuit
EDU
or
Cylinder Recognition Sensor
Charge Circuit Injector
(TDC (G) Sensor )
(Built into ECU )
Engine ECU
Supply Pump
(PCV : HP0, SCV : HP2 · HP3 · HP 4)
Accelerator Position Sensor
Q000875E
Actuation Signal
Actuation Output
ECU EDU
Check Signal
Q000876E
Operation Section
1–2
(2) Operation
• The high-voltage generating device in the EDU converts the battery voltage into high voltage. The ECU sends
signals to terminals B through E of the EDU in accordance with the signals from the sensors. Upon receiving these
signals, the EDU outputs signals to the injectors from terminals H through K. At this time, terminal F outputs the IJf
injection verification signal to the ECU.
Crankshaft Position Sensor Detects the crankshaft angle and outputs the engine speed signal.
(Engine Speed Sensor)
Cylinder Recognition Sensor Identifies the cylinders.
(TDC (G) Sensor)
Accelerator Position Sensor Detects the opening angle of the accelerator pedal.
Intake Air Temperature Sensor Detects the temperature of the intake air after it has passed through the
turbocharger.
Mass Airflow Meter Detects the flow rate of the intake air. It also contains an intake air temperature
sensor that detects the temperature of the intake air (atmospheric temperature).
(1) Crankshaft Position Sensor (Engine Speed Sensor) and Cylinder Recognition
Sensor {TDC (G) Sensor}
Crankshaft Position Sensor (Engine Speed Sensor)
• The crankshaft position sensor is installed near the crankshaft timing gear or the flywheel. The sensor unit is a MPU
(magnetic pickup) type. When the engine speed pulsar gear installed on the crankshaft passes the sensor section,
the magnetic field of the coil within the sensor changes, generating AC voltage. This AC voltage is detected by the
engine ECU as the detection signal. The number of pulses for the engine speed pulsar depends on the
specifications of the vehicle the sensor is mounted in.
Cylinder Recognition Sensor {TDC (G) Sensor}
• The cylinder recognition sensor is installed on the supply pump unit for the HP0 system, but for the HP2, HP3, or
HP4 system, it is installed near the supply pump timing gear. Sensor unit construction consists of the MPU type,
which is the same as for the crankshaft position sensor, and the MRE (magnetic resistance element) type. For the
MRE type, when the pulsar passes the sensor, the magnetic resistance changes and the voltage passing through
the sensor changes. This change in voltage is amplified by the internal IC circuit and output to the engine ECU. The
number of pulses for the TDC pulsar depends on the specifications of the vehicle the sensor is mounted in.
Operation Section
1–2
Amplifier No. 2
Hall Elements (2) 0 50 100
Accelerator Opening (%)Q000879E
Contact Type
- The sensor uses a contact-type variable resistor. Since the lever moves linked with the accelerator pedal, the
sensor resistance value varies with the accelerator pedal opening. Therefore, the voltage passing the sensor
changes, and this voltage is input to the engine ECU as the accelerator opening signal.
(4) Mass Airflow Meter (with Built-In Intake Air Temperature Sensor)
• The mass air flow meter is installed behind the air cleaner and detects the intake air flow (mass flow). This sensor is
a hot-wire type. Since the electrical resistance of the hot wire varies with the temperature, this characteristic is
utilized to measure the intake air quantity. The mass airflow meter also has a built-in intake air temperature sensor
(thermistor type) and detects the intake air temperature (atmospheric temperature).
Intake Air
Temperature Resistance
Sensor +B E2G VG THAF E2
Hot Wire
Temperature C ( F ) Q000882E
VTHW
A-GND
Coolant Temperature
Q000883E
Operation Section
1–2
Resistance - Temperature
Thermistor Characteristic
Resistance Value
Temperature
Q000848E
7. CONTROL SYSTEM
Fuel Injection Timing Control This control replaces the function of the timer in the conventional injection pump.
It achieves optimal injection timing by effecting control in accordance with the
engine speed and the injection quantity.
Fuel Injection Rate Control This function controls the ratio of the fuel quantity that is injected from the orifice
(Pilot Injection Control) of the injector within a given unit of time.
Fuel Injection Pressure Control This control uses the rail pressure sensor to measure the fuel pressure, and it
feeds this data to the engine ECU in order to control the pump discharge
quantity.
(3) Fuel Injection Quantity Control
General Description
• This control determines the fuel injection quantity by adding coolant temperature, fuel temperature, intake air
temperature, and intake air pressure corrections to the basic injection quantity. The engine ECU calculates the
basic injection quantity based on the engine operating conditions and driving conditions.
Injection Quantity Calculation Method
• The calculation consists of a comparison of the following two values: 1. The basic injection quantity that is obtained
from the governor pattern, which is calculated from the accelerator position and the engine speed. 2. The injection
quantity obtained by adding various types of corrections to the maximum injection quantity obtained from the
engine speed. The lesser of the two injection quantities is used as the basis for the final injection quantity.
Operation Section
1–2
Accelerator Opening
Quantity
Injection
Engine Speed
Accelerator Opening
Basic Injection Quantity Low Corrected Injector Actuation
Quantity Final
Side Selected Quantit Period Calculation
Engine Speed Injection
Maximum Injection y
Quantity Individual Cylinder
Correction Quantity
Speed Correction
Injection Pressure Correction
Quantity
Injection
Accelerator Opening
Coolant Temperature
Injection Quantity
High Low
Starting
Base Injection
Quantity
STA ON Time
Injection Quantity
for Maximum Speed Setting
Engine Speed
QB0717E
Corrections
• Cold Engine Maximum Injection Quantity Correction
When the coolant temperature is low, whether during start-up or during normal operation, this correction increases
the injection quantity.
Operation Section
1–2
Injection Quantity
Engine SpeedQ000891E
Engine Speed
Q000892E
Atmospheric Pressure
Correction Quantity
Engine Speed
Q000893E
Injection Quantity
Change in Accelerator
Pedal Position
Injection Quantity
After Correction
Delay
Time
Q000487E
Injection
ECU
+5V
Adjustment
VLQC
Quantity
Correction
Quantity
A-GND
Quantity Adjustment
Resistor Correction Voltage
(4) Fuel Injection Rate Control
• Although the injection rate increases with the adoption of high-pressure fuel injection, the ignition lag, which is the
delay from the start of injection to the beginning of combustion, cannot be shortened to less than a certain period of
time. Therefore, the quantity of fuel injected until ignition takes place increases (the initial injection rate is too high),
resulting in explosive combustion simultaneous with ignition, and an increase in NOx and sound. To counteract this
situation, pilot injection is provided to keep the initial injection at the minimum requirement rate, to dampen the
primary explosive combustion, and to reduce NOx and noise.
Operation Section
1–2
[Ordinary Injection
] [Pilot Injection
]
Injection Rate
Small First-Stage
Large First-Stage Combustion
Combustion
Main
Injection Timing
Engine Speed Basic Injection
Timing Correction
Injection Quantity
Pilot
Injection Timing
BatteryVoltage Correction
IntakeAir PressureCorrection
IntakeAir TemperatureCorrection
Atmospher ic PressureCorrection
Coolant TemperatureCorrection
Engine Speed NE
Pulse
Pilot Interval
Q000896E
Operation Section
1–2
Split Injection
- The purpose of split injection is to improve the startability of a cold engine. Before the conventional main injection
takes place, this function injects two or more extremely small injections of fuel.
Pilot Injection
TDC
TDC (G) Pulse
A B C D
Injection Rate
Q000898E
Automatic ISC
- With automatic ISC, the engine ECU sets the target speed. The target engine speed varies with the type of
transmission (automatic or manual), whether the air conditioner is ON or OFF, the shift position, and the coolant
temperature.
Engine ECU
Q000900E
Manual ISC
- The idle engine speed is controlled by the setting on the idle setting button at the driver's seat.
ECU
Target Engine Speed
A-VCC +5V
V-IMC
A-GND
#1 #3 #4
t1 t3 t4
(Make the t for all the cylinders equal.
)
Angular Speed
#1 #3 #4 #2 #1 #3 #4 #2
(2) Operation
• After the vacuum pump generates a vacuum, the E-VRV (electric-vacuum regulation valve) regulates the vacuum
anddirects it to the diaphragm chamber of the EGR valve. In response to this vacuum, the diaphragm pushes the
spring downward, which determines the opening of the EGR valve and controls the EGR volume.
• The EGR cooler, which is provided in the EGR passage between the cylinder head and the intake passage, cools
theEGR in order to increase the EGR volume.
• The EGR cutoff VSV, which opens the diaphragm chamber to the atmosphere when the EGR valve is closed,
helpsto improve response.
Operation Section
1–1
*1 : The engine ECU outputs sawtooth wave signals with a constant frequency. The value of the current is the effective (average) value of these
signals. For details, see the explanation of the HP3 supply pump and SCV.
(2) Operation
• Signals from the engine ECU actuate the stepping motor, which regulates the throttle valve opening.
EGR Control
• To further increase the EGR volume when the EGR valve is fully open, the vacuum in the intake manifold can be
increased by reducing the throttle valve opening, which restricts the flow of the intake air.
Noise and Exhaust Gas Reduction
• When the engine is being started, the throttle valve opens fully to reduce the emissions of white and black smoke.
• When the engine is being stopped, the throttle valve closes fully to reduce vibration and noise.
• During normal driving, the throttle valve opening is controlled in accordance with the engine conditions, coolant
tem-perature, and atmospheric pressure.
Operation Section
1–1
(2) Operation
• The exhaust gas control system operates when the warm-up switch is ON, and all the conditions listed below have
been met.
Operation Conditions
- The EGR is operating.
Operation Section
1–2
Injection Quantity
Extremely Low Torque
or Engine Speed Range
Engine Speed
Q000907E
Thermistor Element
Resistance Value ( )
Cover
(4) Operation
• By optimizing the injection pattern and controlling the exhaust gas temperature based on the exhaust gas
temperature and the difference in pressure at the front and rear of the DPF, PM is collected, oxidized, and self-
combusted. When the exhaust temperature is low, adding after-injection after the main injection raises the exhaust
gas temperature to approximately 250?C and promotes oxidation of the PM. When the PM is collected and
accumulated, the post-injection is added and HC is added to the catalyst to raise the catalyst temperature to 600?
C, which is the self-combustion temperature for PM. This combusts the accumulated PM in a short time. The
engine ECU controls the A, B, and C times and the injection times.
TDC A
After-Injection Post-Injection
B C
Q000506E
8. DIAGNOSIS
• Erasing DTCs from memory: After reading the DTCs in check mode, erase the DTCs from memory.
• Starting the Engine: Select the check mode and start the engine.
• Malfunctioning system check 1: While the engine is running at idle, shake the wiring harness and connectors of
thesystem that output the malfunction during the diagnosis (check mode) inspection.
• Malfunctioning system check 2: If the MIL (Malfunction Indicator Light) illuminates when the wiring harness and
con-nectors are shaken, there is a poor contact in the wiring harness or connectors in that area.
Operation Section
1–1
DLC1 E1 DLC3
TC
123 4 56 18 16151413121110 9
19
789 101120 87654321
TE1
121314 15 161721 2223
CG
Q000917E
Never connect the wrong terminals of the connectors as this will lead to a malfunction.
Reading DTCs 1
• Turn the ignition switch ON and count the number of times the MIL (Malfunction Indicator Light) blinks
· Normal Operation
0.26sec 0.26sec
Repeat
ON
Malfunction
OFF Indicator Light
0.26sec
Jump Terminals TE1 and TC
OFF
0.52sec 0.52sec
Jump Terminals TE1 and TC Q000918E
• If the MIL (Malfunction Indicator Light) does not output a code (the light does not blink), there may be an open circuit
inthe TC terminal system or a failure in the engine ECU.
Operation Section
1–2
• If the malfunction indicator light is constantly ON, there may be a short (pinching) in the wiring harness or a failure
inthe engine ECU.
• If meaningless DTCs are output, there may be a malfunction in the engine ECU.
• If the MIL (Malfunction Indicator Light) illuminates without outputting a DTC while the engine operates at a
minimumspeed of 1000rpm, turn the ignition switch OFF once; then resume the inspection.
Reading DTCs 2
• If an abnormal DTC has been output, check it against the DTC list.
Erasing DTCs from memory
• Remove the ECD fuse (15A); after 15 seconds have elapsed, re-install the fuse.
Q000919E
After completing the inspection of the ECD system, erase the DTC memory, and make sure the normal code is
output.
8.4 Throttle Body Function Inspection
< CAUTION >
• Be sure to inspect the function of the throttle body after it has been disassembled and reassembled, or after any of
itscomponents have been removed and reinstalled.
• Verifying Throttle Motor: Verify that the motor generates an operating sound when the ignition switch is turned ON.
Also, verify that there is no interference sound.
Operation Section
1–1
(2) Inspection
• Start the engine and make sure the MIL (Malfunction Indicator Light) does not illuminate and the engine speed is
within standards when the air conditioner is turned ON and OFF after the engine has warmed up.
A Type Pump
Mechanical Pump Distributor Type Pump
NB Type Pump
ECD V3 Pump 1 MPa is
2
ECD V Series approximately 10.2kgf/cm
ECD V4 Pump 120
( st ) HP0Pump 120
1 Generation HP2Pump 145
Common Rail Series
( nd ) HP3,4Pump 185
2 Generation
50 100 150 200
Injection Pressure ( MPa )
Q000920E
Injection Quantity
t
Q000921E
• As the injection pressure increases, the injection rate increases accordingly. The increase in injection rate leads to
anincrease in the volume of the air-fuel mixture that is created between the start of injection until ignition (the
ignition lag period). Because this mixture is subsequently combusted at once, it creates noise (diesel knock) and
NOx. For this reason, it is necessary to appropriately control the injection rate by maintaining a low injection rate at
the beginning of injection and supplying a sufficient quantity after the ignition. To meet this need, two-spring
nozzles have been adopted and a pilot injection system has recently been developed.
Injection Quantity
Pilot Injection
Q000922E
Advance
Angle
Angle
Injec Injec
ti onQu tio nQua
antit ntity
y Engine Speed Engine Speed
Q000923E
Q000924E
Repair Section
2–91
Knocking
Sound
Black White
Smoke Smoke
Q002310E
Pressure Increase
Ignition
Start of
Injection
2 Cold Engine
3 Intake air temperature is low. Ignition occurs late without an increase in temperature.
4 Poor Engine Compression
Repair Section
2–92
4 Rise and Fall of Oil Pressure Oil undergoes partial thermal breakdown.
2. DIAGNOSIS OVERVIEW
Repair Section
2–91
Return to step 3.
2.2 Inquiries
z Use the Common Rail System (CRS) troubleshooting questionnaire to consult with the customer and adequately
grasp the malfunction symptoms.
Do not ask random questions. Rather, ask questions that will aid in narrowing down the possible malfunctioning
system while making educated guesses based on the actual symptoms.
Reasons
• There are cases when the malfunction symptoms cannot be reproduced at the service center.
• The customer's complaint is not always limited to the malfunction.
• If the person performing repairs is not working from the correct malfunction symptoms, man-hours will be wasted.
• The questionnaire can aid the service center in diagnosing, repairing and verifying repair work.
Questioning Results
Inspection Results
Q002315E
Repair Section
2–91
(1) Questionnaire
Additional Items
DTC Check
Illuminated No Yes DTC Normal Fuel Pressure when Engine is Stopped
Abnormal DTC (All Codes) 1 Minute after Turning Engine OFF
Malfunction Details: Time of occurrence, place and driving conditions during reoccurrence.
Inspection
Results
Malfunction Symptom
Idle Speed,
No Yes Yes
Malfunction Symptom
Idle Speed,
3.1 DST-2
z The DST-2 can check for DTCs in either normal or check mode. In comparison to the normal mode, the check
mode has higher sensitivity in detecting malfunctions. Check mode is used when detection is not possible in normal
mode, regardless of the assumed abnormality.
NG : - OK : +
Q000916E
• If the DTC cannot be erased, cycle the ignition switch OFF and back ON, and then perform code erasure again.
• Do not use the DST-2 to erase the DTC until the cause of the malfunction is clear.
4. TROUBLESHOOTING BY SYSTEM
NG
1 Clogged air cleaner element Clean or replace the air cleaner.
OK
Repair Section
2–91
NG
2 Check the suction path for leaks. Repair or replace the malfunctioning
• Suction path joints component.
• Suction pipes, hoses
OK
Normal
NG
1 Add fuel fuel
Fuel system check (remaining fuel quantity, or replace components (clean tank.)
properties)
• Check the amount of fuel remaining in
thetank.
• Check the condition of the fuel.
Requestengine analysis from a third party as
necessary.
- Color (no color, brownish, milky)
- Odor (kerosene, heavy oil, irritating odor)
- Separation of materials (water, foreign
objects)
- Viscosity (high/low viscosity, wax
consistency)
OK
NG
2 Fuel tank interior check (modification/additions,
Restore the fuel tank.
position of fuel pipe inlet/outlet, clogging and
holes)
• Check the tank for modifications or additions.
Consult with the user.
- Fuel inlet/outlet position, tank piping
- Foreign material inside the tank, water
separation
- Tank-internal Zn cladding
- Check the tank-internal fuel piping for the
following.
- Inlet/outlet position (below position "E")
- Inlet clogging, bent or deformed piping
(crushed pipe)
- Crushed piping connections
OK
NG
Repair Section
2–92
OK
NG
4 Primary filter, sedimentor check Replace the filter, and drain water from the
sedimentor.
• Check for primary filter clogging and dirt.
• Check sedimentor water volume.
OK
NG
5 Looseness at priming attachment point
Tighten
check
or replace the priming pump.
• Check the following.
- Looseness at the priming attachment
point - Does the piston stick out?
- Fuel leakage (oozing)
OK
NG
6 Filter (supply pump inlet) clogging Clean the gauze filter, fuel filter and fuel piping
• Fuel filter system, or replace the filters.
- Check for fuel delivery from the priming
pump.
• Gauze filter
- Visually check for clogging due to foreign
material.
OK
NG
7 Oil level increase (engine internal leak)
Check the engine.
• Verify whether the oil level increases on the
oil level gauge.
OK
Repair Section
2–91
NG
8 High-pressure piping and CRS Repair component
leaking high-pressure piping or replace
leaking
(injector supply pump, rail) fuel leaks parts.
(engine
external leak) (Refer to "(2) Fuel leak check".)
• Connect the DST-2 to the diagnostic connec-
tor. Activate the "Fuel Leak Check Function"
within the active test.
• Visually check and specify areas that
leakfuel.
< CAUTION >
OK
Normal
Rail Pressure (RP) • Displays the Following engine Fuel pressure in the PCR1, PCR2 signals
fuelpressure in the warm-up, when the rail is displayed within (rail assembly)
a range of 30 MPa to
rail. engine is rotating
160 MPa.
• Display range: 0
MPa to 255 MPa
(2) Fuel leak check
• Connect the DST-2 to the vehicle-side test connector.
• With the vehicle idling, perform the active test by following the instructions on the DST-2 display.
accelerator pedal.
• Verify that there are no fuel system leaks during the active test (when fuel pressure is being applied to the rail.)
The number of each terminal can be seen from the rear side of the wiring harness.
Q002327E
Continuity Check
1) Remove connectors "A" and "C", and then measure
Diagram 2 resistance between the two.
1 1
Sensor up and down, and side-to-side.
2 2 2
C B A
Q002328E
Repair Section
2–91
2) As shown in diagram 2, there is no continuity (open circuit) between terminal 1 of connector "A" and terminal 1 of
connector "C". However, there is continuity between terminal 2 of connector "A" and terminal 2 of connector "C".
Therefore, there is an open circuit between terminal 1 of connector "A" and terminal 1 of connector "C".
Engine
ECU
1 1 1
Sensor
2 2 2
C B A
Q002332E
Short
Sensor Circuit
% $ #
Q002331E
1) Remove connector "A" and connector "C", and then measure the resistance respectively between terminals 1 and
2 of connector "A" and ground.
2) As shown in diagram 6, there is continuity between terminal 1 of connector "A" and the body ground (short circuit).
However, there is no continuity between terminal 2 of connector "A" and the body ground. Therefore, there is a
short circuit between terminal 1 of connector "A" and terminal 1 of connector "C".
Repair Section
2–91
1 1 1 1
Measurement
2 2 2 2 • There is no continuity between termi-
C B2B1 A Results nal 1 of connector "A" and the body
Q002333E
ground.
below. • There is continuity between
terminal1 of connector "B2" and the
body ground.
5. TROUBLESHOOTING
NG
1 Connect the DST-2 and read the DTC.
Inspect the check engine warning light circuit.
OK
NG
1 Use the DST-2 to verify whether Repair
the coolant
the glow control system. (Refer to the
temperature is at the glow system operating
glow control system check procedure issued by
temperature. In addition, verify whether battery
the vehicle manufacturer.)
voltage is being supplied to the glow plugs at
the designated times.
OK
NG
2 Use the DST-2 to monitor engine speed
Check while
the crankshaft position sensor. (Refer to
cranking the engine. Verify whether
the crankshaft
engine position sensor check procedure
speed is being correctly output. issued by the vehicle manufacturer.)
OK
Repair Section
2–92
NG
3 Verify the output waveform of theRepair
cylinder
or replace the cylinder recognition
recognition sensor. (Refer to thesensor
cylinder
and/or the corresponding circuit.
recognition sensor check procedure issued by
the vehicle manufacturer.)
OK
NG
4 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
NG
5 Verify whether there is a start signal
Repairwhen
the start signal circuit.
cranking the engine by checking the engine
ECU start signal terminal.
OK
NG
6 Check the engine ECU power supply. Repair
(Refer
thetoengine ECU power supply.
the engine ECU power supply circuit diagram
issued by the vehicle manufacturer.)
OK
NG
7 Check the supply pump and the supplyRepairpump
or replace the supply pump and drive
drive circuit. (Refer to the supply circuit.
pump drive
circuit diagram issued by the vehicle
manufacturer.)
OK
Troubleshooting complete
NG
1 Verify that the engine is not overheated.
Repair the engine cooling system.
OK
Repair Section
2–91
NG
2 Check the crankshaft position sensor
Repairoutput
or replace the crankshaft position
waveform. (Refer to the crankshaft
sensor
position
and/or the corresponding circuit.
sensor check procedure issued by the vehicle
manufacturer.)
OK
NG
3 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
NG
4 Verify whether there is a start signal
Repairwhen
the start signal circuit.
cranking the engine by checking the engine
ECU start signal terminal.
OK
NG
5 Check the engine ECU power supply. Repair
(Refer
thetoengine ECU power supply.
the engine ECU power supply circuit diagram
issued by the vehicle manufacturer.)
OK
NG
6 Check the supply pump and the supplyRepairpump
or replace the supply pump and drive
drive circuit. (Refer to the supply circuit.
pump drive
circuit diagram issued by the vehicle
manufacturer.)
OK
Troubleshooting complete
NG
1 Use the DST-2 to verify whether Repair
the coolant
the glow control system. (Refer to the
temperature is at the glow system operating
glow control system check procedure issued by
temperature. In addition, verify whether battery
the vehicle manufacturer.)
voltage is being supplied to the glow plugs at
the designated times.
Repair Section
2–92
OK
NG
2 Monitor engine speed while cranking
Check thethecrankshaft position sensor. (Refer to
engine. Verify whether engine speed
the crankshaft
is being position sensor check procedure
correctly output. issued by the vehicle manufacturer.)
OK
NG
3 Verify whether there is a start signal
Repairwhen
the start signal circuit.
cranking the engine by checking the engine
ECU start signal terminal.
OK
NG
4 Check the engine ECU power supply. Repair
(Refer
thetoengine ECU power supply.
the engine ECU power supply circuit diagram
issued by the vehicle manufacturer.)
OK
NG
5 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
NG
6 Check the supply pump and the supplyRepairpump
or replace the supply pump and drive
drive circuit. (Refer to the supply circuit.
pump drive
circuit diagram issued by the vehicle
manufacturer.)
OK
Troubleshooting complete
• Injector
• Supply pump
• Fuel filter
• Engine ECU
• Rail pressure sensor
Clogged air cleaner element
NG
1 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
Repair Section
2–91
NG
2 Check the fuel filter. Replace the fuel filter.
OK
NG
3 Check the supply pump and the supplyRepairpump
or replace the supply pump and drive
drive circuit. (Refer to the supply circuit.
pump drive
circuit diagram issued by the vehicle
manufacturer.)
OK
NG
4 Check the rail pressure sensorRepair and orthe
replace the rail pressure sensor and
corresponding circuit. (Refer to the rail
the pressure
corresponding circuit.
sensor check procedure issued by the vehicle
manufacturer.)
OK
Troubleshooting complete
(6) The engine returns to idle speed too slowly, or does not return at all.
Description
The time required for the engine to return to idle speed is longer than normal, or the engine does not return to idle
speed.
Possible Cause
• Accelerator position sensor
• Injector
• Supply pump
Clogged air cleaner element
NG
1 Perform the accelerator pedal position
Repairsensor
or replace the accelerator position
function check. (Refer to the sensor
accelerator
and/or the corresponding circuit.
position pedal sensor check procedure issued
by the vehicle manufacturer.)
OK
NG
2 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
NG
3 Check the supply pump and the supplyRepairpump
or replace the supply pump and drive
drive circuit. (Refer to the supply circuit.
pump drive
circuit diagram issued by the vehicle
manufacturer.)
OK
Repair Section
2–92
Troubleshooting complete
NG
1 Check parts that may be a source of
Repair
abnormal
the engine.
engine vibration.
OK
NG
2 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
NG
3 Verify that the engine is not overheated.
Repair the engine cooling system.
OK
NG
4 Check the crankshaft position sensor.
Repair
(Refer
or replace
to the crankshaft position
the crankshaft position sensor check
sensor
procedure
and/or the corresponding circuit.
issued by the vehicle manufacturer.)
OK
NG
5 Check the supply pump and the supplyRepairpump
or replace the supply pump and drive
drive circuit. (Refer to the supply circuit.
pump drive
circuit diagram issued by the vehicle
manufacturer.)
OK
Troubleshooting complete
NG
1 Verify that the engine is not overheated.
Repair the engine cooling system.
OK
NG
2 Check the crankshaft position sensor.
Repair
(Refer
or replace
to the crankshaft position
the crankshaft position sensor check
sensor
procedure
and/or the corresponding circuit.
issued by the vehicle manufacturer.)
OK
NG
3 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
NG
4 Verify whether there is a start signal
Repairwhen
the start signal circuit.
cranking the engine by checking the engine
ECU start signal terminal.
OK
NG
5 Check the engine ECU power supply. Repair
(Refer
thetoengine ECU power supply.
the engine ECU power supply circuit diagram
issued by the vehicle manufacturer.)
OK
NG
6 Check the supply pump and the supplyRepairpump
or replace the supply pump and drive
drive circuit. (Refer to the supply circuit.
pump drive
circuit diagram issued by the vehicle
manufacturer.)
OK
Troubleshooting complete
• EGR system
• Injector
• Mass Air Flow (MAF) meter
• Crankshaft position sensor
• Accelerator position sensor
• Boost pressure sensor
• Supply pump
• Start signal circuit
• Air cleaner, duct
Clogged air cleaner element
NG
1 Check for air cleaner clogging and/or
Replace
damage.
the air cleaner or repair the air duct.
OK
NG
2 Verify that the engine is not overheated.
Repair the engine cooling system.
OK
NG
3 Check the crankshaft position sensor.
Repair
(Refer
or replace
to the crankshaft position
the crankshaft position sensor check
sensor
procedure
and/or the corresponding circuit.
issued by the vehicle manufacturer.)
OK
NG
4 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
NG
5 Verify whether there is a start signal
Repairwhen
the start signal circuit.
cranking the engine by checking the engine
ECU start signal terminal.
OK
NG
6 Check the MAF meter and the corresponding
Repair or replace the MAF meter and/or the
circuit. (Refer to the MAF meter corresponding
check circuit.
procedure issued by the vehicle manufacturer.)
OK
NG
7 Check the Exhaust Gas Recirculation
Repair(EGR)
or replace the EGR system.
system. (Refer to the EGR system check
procedure issued by the vehicle manufacturer.)
OK
Repair Section
2–91
NG
8 Perform the accelerator pedal position
Repairsensor
or replace the accelerator position
function check. (Refer to the sensor
accelerator
and/or the corresponding circuit.
position pedal sensor check procedure issued
by the vehicle manufacturer.)
OK
NG
9 Check the boost pressure sensor Repair
and orthereplace the boost pressure sensor
corresponding circuit. (Refer to and/or
the boost
the corresponding circuit.
pressure sensor check procedure issued by the
vehicle manufacturer.)
OK
NG
10 Check the supply pump and the supplyRepairpump
or replace the supply pump and drive
drive circuit. (Refer to the supply circuit.
pump drive
circuit diagram issued by the vehicle
manufacturer.)
OK
Troubleshooting complete
NG
1 Repair the glow control system. (Refer
Repairtothe
theglow control system.
glow control system check procedure issued by
the vehicle manufacturer.)
OK
NG
2 Check the crankshaft position sensor.
Repair
(Refer
or replace
to the crankshaft position
the crankshaft position sensor check
sensor
procedure
and/or the corresponding circuit.
issued by the vehicle manufacturer.)
OK
NG
3 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
Repair Section
2–92
NG
4 Check engine parts that may be a
Repair
source
theofengine.
abnormal combustion.
OK
Troubleshooting complete
• Engine
• Injector
• Supply pump
Clogged air cleaner element
NG
1 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
NG
2 Check the supply pump and the supplyRepairpump
or replace the supply pump and drive
drive circuit. (Refer to the supply circuit.
pump drive
circuit diagram issued by the vehicle
manufacturer.)
OK
NG
3 Check parts that may be a source ofRepair
poor fuel
the engine.
economy.
OK
Troubleshooting complete
2–119
R e p a ir S e c t io n
• Injector
• Supply pump
• EGR system
• Engine ECU
• Electronic control throttle
• Rail pressure sensor
• Mass Air Flow (MAF) meter
• Boost pressure sensor
Clogged air cleaner element
OK
NG
2 Check the electronic control throttle and the
corresponding circuit. (Refer to the electronic
control throttle check procedure issued by the
vehicle manufacturer.)
OK
NG
3 Check the MAF meter and the corresponding
circuit. (Refer to the MAF meter check
procedure issued by the vehicle manufacturer.)
OK
OK
NG
5 Check the boost pressure sensor and the
corresponding circuit. (Refer to the boost
pressure sensor check procedure issued by the
vehicle manufacturer.)
OK
NG
6 Check the rail pressure sensor and the
corresponding circuit. (Refer to the rail pressure
sensor check procedure issued by the vehicle
manufacturer.)
OK
NG
7 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
NG
8 Check the engine ECU power supply. Repair
(Refer
thetoengine ECU power supply.
the engine ECU power supply circuit diagram
issued by the vehicle manufacturer.)
OK
NG
9 Check the supply pump and the supplyRepairpump
or replace the supply pump and drive
drive circuit. (Refer to the supply circuit.
pump drive
circuit diagram issued by the vehicle
manufacturer.)
OK
Troubleshooting complete
Repair Section
2–91
(13) White smoke
Description
White smoke is being exhausted.
Possible Cause
• Fuel filter
• Injector
• Supply pump
• EGR system
• Engine ECU
• Electronic control throttle
• Rail pressure sensor
Clogged air cleaner element
NG
1 Check the fuel filter. Replace the fuel filter.
OK
NG
2 Check each injector. (Refer to the injector
Repair or replace the injector and/or the
check procedure issued by the vehiclecorresponding circuit.
manufacturer.)
OK
NG
3 Check the Exhaust Gas Recirculation
Repair(EGR)
or replace the EGR system.
system. (Refer to the EGR system check
procedure issued by the vehicle manufacturer.)
OK
NG
4 Check the supply pump and the supplyRepairpump
or replace the supply pump and drive
drive circuit. (Refer to the supply circuit.
pump drive
circuit diagram issued by the vehicle
manufacturer.)
OK
NG
5 Check the rail pressure sensorRepair and orthe
replace the rail pressure sensor and
corresponding circuit. (Refer to the rail
the pressure
corresponding circuit.
sensor check procedure issued by the vehicle
manufacturer.)
OK
NG
6 Check the electronic control throttle
Repair
andorthe
replace the electronic control throttle
corresponding circuit. (Refer to the
and/or
electronic
the corresponding circuit.
control throttle check procedure issued by the
vehicle manufacturer.)
OK
Troubleshooting complete
Repair Section
2–92
5.2 Other Malfunction Symptoms
Malfunctions caused by components other than the CRS z There are occasions when a malfunction that
appears to be generated by the CRS is actually caused by a different component or system. For instance, engine
mechanical parts and the fuel system may cause malfunction symptoms identical to symptoms generated by the CRS.
When troubleshooting, do not simply assume that the source of a malfunction is the CRS. Consider all causes should
be exhaustively considered while verifying the list below.