Page 160 of 1082
03-250000-00
Crankshaft position sensor
Measuring engine rpmT-MAP sensor
Measuring booster pressure
and temperatureHFM
Measuring intake air mass and
temperature
Engine ECU (D20DTF)
Engine control by various
signals
Fuel filter assembly
Supply clean fuel/fuel
heating/water separation by
priming pumpAccelerator pedal
position sensor
Detects driver's intention for
speed up/downHigh pressure pump
Generates the high pressurized fuel
and supply it.
Plunger type HP pump (1,800
bar)
Vane type transfer pump (6bar)
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08-70000-00
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 o
r
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. -
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Page 229 of 1082
10-51413-00
1. OVERVIEW
The pre-heating system for D20DTF 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 plugGlow plug control unit
(GCU)
Glow indicatorEngine ECU (D20DTF)
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10-10
4) System Operation
Glow plug is installed in the cylinder head. It enhances the cold starting performance and reduces the
exhaust gas during cold starting.
ECU receives the various signals such as engine rpm, coolant temperature and vehicle speed through
CAN communication lines. GCU controls the pre-heating, cranking and post-heating operations and
monitors the glow plug. If GCU detects a problem, it sends the result to ECU.
(2) Operation of AQGS
Duty control area:
Between 5 and 100%
Frequency: 20 Hz
Duty ratio = (RMS voltage)²
(Battery voltage)² 1.
2.
3.
(1) Characteristics of temperature and current in AQGS
AQGS unit increases the glow plug temperature very rapidly (1,000˚C in 2 seconds).
FET (similar to transistor) for each cylinder in AQGS unit pre-heats the glow plug.
If the glow plug temperature reaches to target temperature, the temperature is controlled by
duty ratio. 1.
2.
3.
AQGS PWM ControlActual voltage pattern
AQGS unit supplies the power to glow plug. This shows the voltage and time
supplied by AQGS by steps. As shown
on the graph, the supplied voltage is
decreased as the steps are continued.
The 3rd step is to keep the temperature,
not to raise it.
Frequency: 20~33Hz
PWM Control duty ratio
- 1st step: 100%
- 2nd step: 35%
- 3rd step: 23%
Page 235 of 1082
10-111413-00
(3) Operating Steps
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 glow plug
<009b0096004700580057005700570b450047008900a00047009b008f008c004700970099008c008f008c0088009b00900095008e00470099008c0098009c008c009a009b0047008d0099009600940047009b008f008c0047008c0095008e00900095008c00
47006c006a007c00470089008c008d00960099008c0047009a>tarting.
- The time for pre-heating is controlled by the ECU.
If the input voltage (VB) is 11.5 V or less, GCU supplies the battery voltage for preheating time (T1).
If the input voltage (VB) is greater than 11.5 V, GCU supplies the voltage of 11.5 V for preheating time
(T1). -
-
The preheating time may vary according to the conditions.
Input voltage
VB (V)Pre-heating time T1
(sec)
6 8.27
7 5.8
8 4.1
9 3.15
10 2.4
11 1.95
≥ 11.5 1.9
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10-12
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.
During 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 preheating request from the
engine ECU.
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 preheating (Step 3) for 30 seconds.
Page 237 of 1082
10-131413-00
Normal operating mode ▶
This shows the components of preheating system in the pre-heating and the post-heating steps.
Page 242 of 1082

11-6
2. OPERATING PROCESS
1) System Layout
(1) Engine start
SKM performs the authentication process for the SMART key and sends the engine start request to
EMS if there is a normally coded SMART key when pressing the Engine Start/Stop button with the
<0089009900880092008c00470097008c008b008800930047008b008c00970099008c009a009a008c008b004700880095008b0047008e008c008800990047009a008f0090008d009b00470093008c009d008c0099004700900095004702c8007702c9004700
960099004702c8007502c9004700970096009a0090009b0090>on.
SKM sends the start request signal to PCAN network and the cranking request to BCAN network by
“SMART key location” signal when receiving the engine start signal by Engine Start/Stop
button.
SKM turns off the IGN2/ACC relay during cranking to shut down the electric loads.
SKM receives the starting status signal from EMS throug PCAN.
<0068008d009b008c00990047008a009900880095009200900095008e00530047007a007200740047009b009c00990095009a0047009600950047009b008f008c00470068006a006a00560070006e0075005900470099008c0093008800a000470088009500
8b0047009a008c0095008b009a0047009b008f008c00470097>ower status signal of “IGN
after started” through BCAN.
EMS starts to crank the engine after checking the pre-heating condition if it receives the engine
cranking request 1 when pressing the Engine Start/Stop button. EMS starts to crank the engine
immediately if it receives the engine cranking request 2 when pressing the Engine Start/Stop button. 1.
2.
3.
4.
5.
6.
Engine cranking request 1: when pressing the Engine Start/Stop button shortly in normal
conditions
Engine cranking request 2: when pressing the Engine Start/Stop button again after first press or
when pressing the Engine Start/Stp button for more than 3 seconds -
-
Engine start during driving 7.
When pressing the Engine Start/Stop button with IGN ON, the engine start is requested if the
<009d008c008f0090008a0093008c0047009a0097008c008c008b00470090009a00470093008c009a009a0047009b008f008800950047005800570047009200940056008f0047009600990047009500960047009a0090008e00950088009300530047009b00
8f008c0047008e008c008800990047009a008f0090008d009b> lever is in ‘N” position and
the brake switch is ON (no need authentication for 30 seconds).
When pressing the Engine Start/Stop button with IGN ON, the engine start is requested
regardless of brake signal if the vehicle s
p<008c008c008b00470090009a00470096009d008c00990047005800570047009200940056008f004700880095008b0047009b008f008c0047008e008c008800990047009a008f0090008d009b00470093008c009d008c009900470090009a00470090009500
47>‘
position (no need authentication for 30 seconds).
Except input of brake switch signal
In vehicle equipped with A/T, when pressing the Engine Start/Stop button for more than 10
seconds with ACC ON, the engine start is requested regardless of brake signal if the gear shift
lever is in “P” or ‘N” position in IGN ON. -
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*
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