Page 339 of 796

15-110000-00
2) ECU Control
(1) Function
a. ECU Function
ECU receives and analyzes signals from various sensors and then modifies those signals into
permissible voltage levels and analyzes to control respective actuators.
ECU microprocessor calculates injection period and injection timing proper for engine piston speed
and crankshaft angle based on input data and stored specific map to control the engine power and
emission gas.
Output signal of the ECU microprocessor drives pressure control valve to control the rail pressure and
activates injector solenoid valve to control the fuel injection period and injection timing; so controls
various actuators in response to engine changes. Auxiliary function of ECU has adopted to reduce
emission gas, improve fuel economy and enhance safety, comforts and conveniences. For example,
there are EGR, booster pressure control, autocruise (export only) and immobilizer and adopted CAN
communication to exchange data among electrical systems (automatic T/M and brake system) in the
vehicle fluently. And Scanner can be used to diagnose vehicle status and defectives.
Operating temperature range of ECU is normally -40 to +85°C and protected from factors like
oil, water and electromagnetism and there should be no mechanical shocks.
To control the fuel volume precisely under repeated injections, high current should be applied instantly
so there is injector drive circuit in the ECU to generate necessary current during injector drive stages.
Current control circuit divides current applying time (injection time) into full-in-current-phase and hold-
current-phase and then the injectors should work very correctly under every working condition.
b. Control Function
Controls by operating stages
To make optimum combustion under every operating stage, ECU should calculate proper injection
volume in each stage by considering various factors.
Starting injection volume control
During initial starting, injecting fuel volume will be calculated by function of temperature and engine
cranking speed. Starting injection continues from when the ignition switch is turned to ignition
position to till the engine reaches to allowable minimum speed.
Driving mode control
If the vehicle runs normally, fuel injection volume will be calculated by accelerator pedal travel and
engine rpm and the drive map will be used to match the drivers inputs with optimum engine power. -
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15-38
Relay box
A/C
compressorHFM (intake air
temperature)Cooling fan
module
MB 5 A/T (ATF
temperature)Coolant
temperature
sensor
(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
D20DTR ECU
Refrigerant
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15-40
D. Cooling fan and A/C compressor control
Conditions for cooling fan control ▶
The PWM cooling fan is set by coolant temperature and A/C refrigerant pressure. And, the setting
value in A/T equipped vehicle may vary according to the internal oil temperature. The The engine ECU
controls the PWM cooling fan unit based on various signals to get the optimized temperature during
engine running.
PWM cooling fan control according to coolant temperature and vehicle speed -
The PWM cooling fan starts running
from 89℃ of coolant temperature
PWM cooling fan control according to transmission fluid temperature (A/T)
1. PWM duty under 129℃: 0%
2. PWM duty over 130℃: 94.4% -
PWM cooling fan control according to A/C refrigerant pressure -
PWM duty value sharply increases
when the A/C refrigerant pressure
goes over 10 bar. And, it slowly
decreases when A/C refrigerant
pressure goes down below 14 bar
(A/C compressor OFF). PWM duty
Refrigerant
pressure (bar)under 101℃: The PWM dut
y value
decreases when the vehicle speed
increases
over 105℃: The PWM duty value
is fixed at 94.4% -
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Page 377 of 796

15-490000-00
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. *
Page 380 of 796
01-50000-00
No. FUNCTION No. FUNCTION
1 HFM sensor 12 Intake manifold
2 Intake air duct 13 Connecting rod
3 Resonance flap 14 Exhaust manifold
4 Cylinder head cover 15 Crankshaft
5 Exhaust camshaft 16 Engine mounting
6 Intake camshaft 17 Starter
7 Cylinder head 18 Crankcase
8 Spark plug connector 19 Oil pump sprocket
9 Valve tappe
t20 Oil strainer
10 Injector 21 Oil pan
11 Exhaust valve 22 Drain plug
Front View ▶
Page 382 of 796

01-70000-00
2. DESCRIPTION AND OPERATION
1) Cleanliness and Care
An automobile engine is a combination of many machined, honed, polished and lapped surfaces with
tolerances that are measured in the ten-thousandths of an inch. When any internal engine parts are
serviced, care and cleanliness are important. A liberal coating of engine oil should be applied to friction
areas during assembly, to protect and lubricate the surfaces on initial operation.
Proper cleaning and protection of machined surfaces and friction areas is part of the repair procedure.
This is considered standard shop practice even if not specifically stated.
Whenever valve train components are removed for service, they should be kept in order.
They should be installed in the same locations, and with the same mating surfaces, as when they were
removed. Battery cables should be disconnected before any major work is performed on the engine.
Failure to disconnect cables may result in damage to wire harness or other electrical parts.
2) On-Engine Service
Disconnect the negative battery cable before removing or installing any electrical unit, or when a
tool or equipment could easily come in contact with exposed electrical terminals.
Disconnecting this cable will help prevent personal injury and damage to the vehicle.
The ignition must also be in LOCK unless otherwise noted.
Notice Any time the air cleaner is removed, the intake opening -
Any time the air cleaner is removed, the intake opening should be covered. This will protect
against accidental entrance of foreign material, which could follow the intake passage into the
cylinder and cause extensive damage when the engine is started. -
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08-6
3. IGNITION SYSTEM OPERATION
This ignition system does not use a conventional distributor and coil. It uses a crankshaft position
sensor input to the Engine Control Module (ECM).
The ECM then determines Electronic Spark Timing (EST) and triggers the electronic ignition system
ignition coil.
This type of distributor less ignition system uses a "waste spark" method of spark distribution. Each
cylinder is paired with the cylinder that is opposite it (2.3L DOHC: 2 - 3 or 1 - 4, 3.2L DOHC: 1 - 6 or 2 -
5 or 3 - 4).
The spark occurs simultaneously in the cylinder coming up on the compression stroke and in the
cylinder coming up on the exhaust stroke.
The cylinder on the exhaust stroke requires very little of the available energy to fire the spark plug.
The remaining energy is available to the spark plug in the cylinder on the compression stroke. These
systems use the EST signal from the ECM to control the EST.
The ECM uses the following information: Engine load (mass air flow sensor, manifold air pressure
sensor).
Engine coolant temperature.
Intake air temperature.
Crankshaft position.
Engine speed (rpm).
1) Electronic Ignition System Ignition Coil
The Electronic Ignition (EI) system ignition coil is located on the cylinder head cover.
The double ended coils receive the signal for the ECM which controls the spark advance. Each
EI system ignition coil provides the high voltage to two spark plugs simultaneously;
3.2L DOHC
T1/1: cylinder 2 and 5
T1/2: cylinder 3 and 4
T1/3: cylinder 1 and 6
The EI system ignition coil is not serviceable and must be replaced as an assembly.
Page 477 of 796

03-37010-06
1. SPECIFICATIONS
Item Item Specification
Immobilizer
unitOperating voltage
(CAN) 6.0 V to 16.0 V
(6.0 V ~18.0 V)
Operating temperature-30℃ ~ 80℃
Coil inductance420 uH ± 20 uH
Modulation methodFSK
(Frequency Shift Keying : frequency
displacement)
Frequency134.2 KHz ± 4 KHz
TransponderFrequency134.2 KHz ± 4 KHz
Operating temperature-40℃ ~ +85℃
Transponder coding Up to 5
2. CAUTIONS
The vehicle owner must observe the service works when deleting the transponder codes or
registering additional keys.
In any cases, the immobilizer system can not be removed from the vehicle. If you attempt to
remove it and damage the system, starting will be impossible, so never attempt to remove,
damage or modify it.
The remote engine starter cannot be installed to the vehicle equipped with the immobilizer
system.
Do not drop or shock to the transponder in the ignition key as it may be damaged.
With a damaged transponder, the engine cannot be started.
For the vehicle with the immobilizer, there can be a problem in starting the vehicle or the system
error: 1.
2.
3.
4.
5.
6.
When more than one immobilizer keys come into contact with (each) other(s) or key is close
to any device sending or receiving electromagnetic fields or waves
When the ignition key is close to any electronic or electric devices such as lighting equipment,
security keys or security cards
When the ignition key is close to a magnetic or metal object or a battery -
-
-