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15-34
HFM (intake air
temperature)CDPF
Electric throttle
bodyCoolant
temperature senso
r
Oxygen sensor
Injector (C3I)
E-EGR valve
(11) Wide band oxygen sensor control
A. Overview
For diesel engine, combustion is not performed at the optimum (theoretically correct) air-fuel ratio
and the oxygen concentration is thin in most cases. So the wide-band oxygen sensor is used for
this kind of engine, and this sensor is a little different from the one that used for gasoline engine.
The combustion in diesel engine is controlled by fuel injection volume. Therefore, the wide band
oxygen sensor should be used in diesel engine. This sensor measures the air-fuel ratio in very
wide range, and is also called full range oxygen sensor.
The wide band oxygen sensor measures the oxygen density in exhaust gas and sends it to
ECU to control the EGR more precisely. -
B. Components
D20DTR ECU
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15-370000-00
HFM (intake air
temperature)Cooling fan module
DSI 6 A/T (ATF
temperature)Coolant
temperature senso
r
Refrigerant
pressure sensor
Relay box
(12) Cooling fan control
A. Overview of cooling fan and A/C compressor
The cooling system maintains the engine temperature at an efficient level during all engine
operating conditions. The water pump draws the coolant from the radiator. The coolant then
circulates through water jackets in the engine block, the intake manifold, and the cylinder head.
When the coolant reaches the operating temperature of the thermostat, the thermostat opens.
The coolant then goes back to the radiator where it cools. The heat from automatic transmission
is also cooled down through the radiator by circulating the oil through the oil pump. ECU controls
the electric cooling fans with three cooling fan relays to improve the engine torque and air
conditioning performance.
For detailed information, refer to Chapter "Air Conditioning System".
B. Components
A/C compressor
D20DTR ECU
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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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15-430000-00
(14) Immobilizer control
A. Overview
The Immobilizer System provides an additional theft deterrent to the vehicle in which it is installed
and prevents it from being started by unauthorized persons. The transponder integrated in the key
and the engine control unit have the same code. When the ignition key with the integrated
transponder is turned to the ON position, the ECU (Engine Control Unit) checks the crypto code
of the key and, if correct, allows the vehicle to start the engine.
For details, refer to Chapter "Immobilizer".
B. Components
Basic components (ignition key system) ▶
D20DTR ECUImmobilizer antennaInstrument cluster
Immobilizer keyStart motor
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15-44
Key approval process ▶
When turning the ignition switch to ON position, the power is supplied to BCM and ECU. ECU
communicate with the immobilizer key to check if it is valid crypto code. If it is valid, ECU start to
control the engine when turning the ignition switch to START position. The system has 10
seconds of valid time-out period. If the engine does not start in this period, the key approval
process should be done again.
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15-450000-00
(15) CDPF control
A. Overview
As the solution for environmental regulations and PM Particle Material) of diesel engine, the low
emission vehicle is getting popular. This vehicle is equipped with an extra filter to collect the soot
and burn it again so that the amount of PM in the exhaust gas passed through the DOC (Diesel
Oxidation Catalyst) is reduced. The CDPF (Catalyst & Diesel Particulate Filter) is an integrated filter
including DOC (Diesel Oxidation Catalyst) and DPF (Diesel Particulate Filter).
For details, refer to Chapter "CDPF".
B. Components
Oxygen
sensorFront
EGT sensorCDPF
(DOC + DPF)Rear
EGT sensor
Differential pressure
sensorD20DTR ECUElectric throttle body
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15-470000-00
Diff. pres. sensor: Measure
pressure between front sid
e
and rear side of CDPF
ECU (DCM 3.7)
Injector: Control post
injection
D. Operation process
When the differential pressure sensor detects the pressure difference between the front and the
rear side of CDPF, the sensor sends signal indicating the soot is accumulated and the post
injection is performed to raise the temperature of exhaust gas. The amount of fuel injected is
determined according to the temperature of exhaust gas detected by the rear temperature sensor.
If the temperature is below 600°C, the amount of fuel injected is increased to raise the
<009b008c00940097008c00990088009b009c0099008c005500470070008d0047009b008f008c0047009b008c00940097008c00990088009b009c0099008c00470090009a00470096009d008c00990047005d0057005700b6006a00530047009b008f008c00
47008800940096009c0095009b00470096008d0047008d009c>el injected is decreased or not
controlled. When the engine is running in low load range, the amount of post injection and the
amount of intake air are controlled. It is to raise the temperature by increasing the amount of fuel
while decreasing the amount of intake air.
Front EGT sensor: Measure
DOC temp.
Rear EGT sensor: Measure
DPF temp.
Electronic throttle body
Control intake air mass
T-MAP sensor
Intake air
mass
Exceed PM
limitBooster
pressure/
temperaturePost injection
Control intake
air mass
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04-10
3) PWM Electric Fan
(1) Advantages and Disadvantages of the PWM Electric Fan
Advantages ▶
Enhanced A/C performance: at low speed,
at idling, driving in city
Reduction of vibration/noise: fan activated
by PWM only when necessary
Reduction of engine consuming power
(V/Fan driving force) by 4 Hp - Cost
saving -
-
-
Disadvantage ▶
Poor engine cooling perfomance at low
and high rpm -
4) PWM (Pulse Width Modulation) Unit
It controls the time of the output voltage to
control the fan motor speed independently.
Internal functions ▶
Motor power shutting-off function when
overcurrent is applied
Adverse voltage prevention function
Detection function for the motor lock
Temperature detecting function: The
electric fan operates at FULL speed to
cool down the PWM unit when the interior
temperature of PWM unit is over
120~150°C.
Communication function when failing: The
fail signal is transmitted to the ECU when
the PWM unit is malfunctioning.
Soft start function: The motor speed is
gradually increased when the motor is
initially operated. -
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-
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