Page 269 of 715

08-4
2. INSPECTION
Possible Cause Action
Coolant level
is
too low- Leak from the radiator
- Leak from the coolant auxiliary tank
- Leak from the heater core- Change the radiator
- Change the coolant auxiliary tank
- Change the heater
- Leak from the coolant hose
connections
- Damaged coolant hose - Reconnect the hose or replace
the clamp
- Change the hose
- Leak from the water pump gasket
- Leak from the water pump internal
seal- Change the gasket
- Change the water pump
- Leak from the water inlet cap
- Leak from the thermostat housing- Change the water inlet cap
gasket
- Change the thermostat sealing
- Incorrect tightening torque of the
cylinder head bolts
- Damaged cylinder head gasket- Tighten the bolts to the specified
torque
- Change the cylinder head gasket
Coolant
temperature is
too high- Coolant leakage (Coolant level is low)
- Improper coolant mixture ratio
- Kinked coolant hose- Add coolant
- Check the coolant concentration
(Anti-freeze)
- Repair or replace the hose
- Defective thermostat
- Defective water pump
- Defective radiator
- Defective coolant auxiliary tank or tank
cap- Change the thermostat
- Change the water pump
- Change the radiator
- Change the coolant auxiliary tank
or tank cap
- Cracks on the cylinder block or
cylinder head
- Clogged coolant passages in the
cylinder block or cylinder head- Change cylinder block or cylinder
head
- Clean the coolant passage
- Clogged radiator core - Clean the radiator core
- Improper operation of cooling fan - Replace the cooling fan or repair
the related circuit
- Defective temperature sensor or
faulty wiring- Replace the sensor or repair the
related wiring
Coolant
temperature is
too low- Thermostat is stuck open - Change the thermostat
- Improper operation of cooling fan - Replace the cooling fan or repair
the related circuit
- Defective temperature sensor or faulty
wiring- Replace the sensor or repair the
related wiring
Page 272 of 715

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. -
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Page 308 of 715
13-31793-00
1. SPECIFICATION
Item Specification
E-EGR valve Motor EGR response time 50 ms
Driven by DC motor
Valve EGR gas flow rate 120 Kg/h
Position sensor Sensing type Hole sensor
Supplied voltage5V ± 10%
Maximum signal
range5% ~ 95%
Maximum power
consumption<15mA
E-EGR cooler Cooling capacity 8.3 kW or more
Cooling fin type Wavy fin
Cooler type U-shaped
E-EGR bypass valve Driven by Vacuum
(Solenoid valve)
Page 335 of 715
15-10
(3) Components for ECU Output
CAN
E-EGR cooler
bypass valve
- TCU
- Self diagnosis
Cooling fan
E-EGR valve
Variable swirl
valveE-VGT actuatorIMV valve
A/C
compressorInjectorThrottle position
sensor
- ABS & ESP unit
- GCU
- Indicator/Warning Lamp, Meter Cluster
PTC heater
Page 363 of 715

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
Page 364 of 715
15-390000-00
C. Input/Output for cooling fan and A/C compressor
Page 365 of 715

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 duty value
decreases when the vehicle speed
increases
over 105℃: The PWM duty value
is fixed at 94.4% -
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Page 366 of 715
15-410000-00
A/C compressor OFF conditions ▶
Coolant temperature: below -20℃ or over
115℃
Engine rpm: over 4500 rpm
Engine rpm: below 600 rpm
When abrupt acceleration
Very high load during idling
Refrigerant pressure: over 32 bar or below 2
bar
Failure in refrigerant sensor, coolant
temperature sensor, and cooling fan -
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