Page 206 of 828
03-232210-01
Accelerator pedal position
sensor
Detecting driver's intention
for speed up/down
Fuel rail assembly
Relieving the pulsation.
Measuring the fuel pressure.
Distributing the fuel to injectors.
Fuel filter assembly
Supplying clean fuel/fuel
heating/water separation by
priming pump
Plunger type HP pump (1,800 bar)
Vane type LP pump (6 bar)
T-MAP sensor
Measuring booster pressure
and temperature
High pressure pump
Generating high pressurized fuel
and supplying it according to
engine rpm, required volume,
required pressure
Page 250 of 828

08-71520-00
3. CAUTIONS
If 100% of anti-freeze is added, the water pump vane can be damaged and thermal
conductivity can be decreased resulting in poor circulation in the cooling system which leads
to overheated engine.
Use of non-recommended coolant could cause damage to the cooling system and
overheating of the engine.
Opening the coolant reservoir cap while the engine is running or hot can cause burns by hot
steam or water.
To open the coolant reservoir cap, wrap the cap with a wet towel or thick cloth after the
engine is cooled down sufficiently.
If cool water is added to the heated engine, the engine or radiator can be deformed.
The anti-freeze in the coolant can damage the painted surface, so avoid the contact of the
coolant to the painted body.
The anti-freeze and water should be mixed in proper mixture ratio. Never add only water
when adding coolant.
If the anti-freeze content is too low, the coolant can be frozen while the engine can be
overheated if anti-freeze content is too high. -
-
-
-
-
-
-
-
Page 265 of 828
10-4
Glow plug control unit
(GCU)
1. OVERVIEW
The pre-heating system for D20DTR engine has the glow plug to the cylinder head (combustion
chamber), and improves the cold start performance and reduces the emission level.
The pre-heating resistor (air heater) is used to heat the intake air.
This enables the diesel fuel to be ignited in low temperature condition.
The ECU receives the information such as, engine rpm, coolant temperature, engine torque, etc.,
through CAN communication during pre-heating process; and the pre-heating control unit
controls the pre-heating, heating during cranking and post-heating by the PWM control.
Glow plug
Glow indicatorEngine ECU (D20DTR)
Page 268 of 828

10-71413-00
4) Operation
Glow plug is installed in the cylinder head. It enhances the cold starting performance and reduces
the exhaust gas during cold starting.
(1) Operation
Duty control area:
Between 5 and 100%
Frequency: 20 Hz
Duty ratio = (RMS voltage)²
(Battery voltage)² 1.
2.
3.
Pre-Glow: Step 1 ▶
If normal communication with the ECU is established 2 seconds after the power is supplied to the
IGN terminal from the battery, the GCU supplies the battery power to raise the temperature of the
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47009b008f008c0047008c0095008e00900095008c0047006c>CU before starting.
Pre-
heatingCoolant
temperature-30°C -25°C -20°C -10°C -5°C 0°C 20°C
Operating time
28 s 25 s 15 s 5 s 2 s 2 s 0 s
Operating
conditions- IGN: ON
- B+: below 15.2 VStop
conditions- Time-out
- IGN: OFF
- when engine cranking
If the input power (VB) is 11.5 V or less, the GCU supplies the battery power for arrival time
(T1).
If the input power (VB) is greater than 11.5 V, the GCU supplies the voltage of 11.5 V for arrival
time (T1). 1.
2.
- The time for pre-heating is controlled by the ECU.
The time for pre-heating by coolant temperature can vary slightly depending on e.g. other
vehicle operation elements.
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10-8
During cranking: Step 2 and step 3 ▶
Step 2: If the ECU receives the cranking signal after pre-heating (step 1), the GCU supplies the
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8c0047009b00960047005800530058005700570b450055>
Step 3: The GCU supplies the voltage of 5.1 V to keep the temperature at 1,000°C. 1.
2.
Under fixed temperature: The AQGS unit supplies power for 30 seconds (Step 1 + Step 3)
if no cranking signal is received after the step 1.
At cranking: The step 3 is started after the step 2. *
*
Post-glow: Step 4: ▶
The post-heating is for reducing HC/CO after the engine is started. If the time for post-heating
exceeds 180 sec., the GCU unit cuts off the power to each glow plug even if there is pre-heating
request from the engine ECU.
Post-
heatingOperating time
(approx.)-20°C -10°C 0°C 20°C 80°C
Operating time
(approx.)100 s 50 s 25 s 10 s 10 s
Emergency glow ▶
If no CAN signal is received for 4 seconds from the engine ECU after the IGN ON signal is input,
the GCU performs emergency preheat (Step 3) for 30 seconds.
P1 to P2: Pre glow
P3 to P4: Post glow
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14-112412-02
Front temperature sensor
Measures the temperature of
exhaust gas.
This sensor is located at the rear
side of exhaust manifold and
monitors the temperature of
combusted gas to prevent the
exhaust system from overheating.
When the temperature gets
higher, this sensor cuts off the
fuel delivery and controls the EGR
to lower the temperature.Rear temperature sensor
Measure the outlet
temperature of DOC.
This sensor is located at
the rear side of DOC and
monitors the overheating of
CDPF and post injection
volume.
Engine ECU (D20DTR)
Differential pressure sensor
Measures the difference between
inlet and outlet pressures of
CDPF.
If the difference is higher than the
specified value when collecting
the PM, this makes the post
injection for forced recycling of
PM.
T-MAP sensorIntake air
mass
Measures
the
excessive
amount of
PM.
Boost
pressure/
temperature
Injector (C31)
Controls the post injection.
Electric throttle body
Controls the intake air
mass.
HFM sensor
Wide band
oxygen sensor
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15-40
Relay box in engine compartment
(13) High speed
A. Overview
The supplementary electrical heater is installed in DI engine equipped vehicle as a basic
equipment. The PTC system is operated according to two temperature values measured at the
coolant temperature sensor and HFM sensor. This device is mounted in the heater air outlet and
increase the temperature of air to the passenger compartment. Because PTC system is heated by
electrical power, high capacity alternator is required. PTC does not operate during engine
cranking, while the battery voltage is lower than 11 V or during preheating process of glow plugs.
B. Components
HFM (intake air
temperature)
Coolant temperature
sensorPTC heater
PTC 2 relay (PTC
heater 2, 3)
PTC heater
3 (40A)
PTC heater
2 (40A)
PTC heater
1 (40A)
D20DTR ECU
PTC 1 relay
(PTC heater 1)
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15-48
E. Cautions
Use only specified Engine Oil (approved by MB Sheet 229.51) for CDPF. -
Use only specified engine oil (Low Ash Oil) ▶
The vehicle equipped with CDPF should use specific engine oil to improve the engine
performance and fuel economy, and ensure the service life of CDPF. -
Issue with normal engine oil ▶
Sulfur, one of the contents of engine oil is burned and generates soot that is not regenerated
by the DPF. This remains on the filter as ashes and keeps accumulating. Eventually, this
ashes will block the filter. -
Benefit for specified engine oil ▶
Minimized the sulfur content of engine oil which reduces the service life.
Improved fuel economy and emission level of CO2 with high performance and low viscosity.
Increased service life of engine oil with high resistance to temperature. -
-
-
Problems when using unspecified engine oil ▶
The service life of filter may be reduced by 30% or more by the ashes accumulated on the
filter.
The fuel economy may be reduced because of engine rolling resistance, frequent
regeneration of DPF. -
-
These problems are also caused by oil with high sulfur content, such as tax exemption oil
and heating oil, etc. *