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HFM
(Intake air temp.)Coolant temp.
sensor
(9) PTC heater control
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
PTC heater
D20DTF
ECU
Engine room relay box
A: PTC 1 (changeable)
B: PTC 2,3 (not changeable)
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c. Operation process
The ceramic PTC has a feature that the resistance goes up very high at a certain temperature. There
are three circuits in PTC heater. Only one circuit is connected when PTC1 relay is ON, and two circuits
are connected when PTC2 relay is ON.
<00760097008c00990088009b0090009600950047009700990096008a008c009a009a006100470099008c0088008a008f008c009a00470088009b004700880047008a008c0099009b0088009000950047009b008c00940097008c00990088009b009c009900
8c02e7008f0090008e008f00470099008c009a0090009a009b>ance→low current→less heat
<00990088008b00900088009b00900096009502e7009b008c00940097008c00990088009b009c0099008c0047008b0096009e009502e7008f0090008e008f00470099008c009a0090009a009b00880095008a008c02e7008f0090008e008f0047008a009c00
990099008c0095009b02e7009b008c00940097008c00990088>ture up
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d. Control conditions
Operation Operating condition PTC Heater
HI
(PTC2)- Coolant temperature < 15℃
PTC HI ON
LO
(PTC1)- Coolant temperature 15℃ ≤ 65℃, intake air
temperature ≤ -10℃
- Coolant temperature 15℃ < 65 to 60℃, intake air
temperature <-10℃ to 0℃
- Coolant temperature 15℃ ≤ 60℃, intake air
temperature ≤ 0℃ to 5℃PTC LO ON
Stop- A/C blower switch OFF
- Defective ambient air temperature sensor
(including open or short circuit)
- Engine cranking
- Low battery voltage (below 11V)
- During pre-glow process (glow indicator ON)
Operation diagram for PTC heater LO (step 2) ▶
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Meter clusterImmobilizer
antenna
(10) 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 "BCM".
b. Components
Basic components (ignition key system) ▶
Immobilizer key
Start motor
BCM
ECU
D20DTF
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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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c. Components for immobilizer with Smart key system
Components (For antenna, refer to Chapter “SKM”) ▶
Smart key slot
Smart key
Start motor
Meter
cluster
BCM
SKMD20DTF
ECU
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Key approval process in Smart key system equipped vehicle
The key approval consists of two processes; immobilizer key approval and Smart key
approval. ▶
Immobilizer key approval: When inserting the Smart key into Smart key slot, the power is supplied to the
key slot. SKM communicate with the Smart key in key slot to check if it has valid crypto code. If it is valid,
ECU start to control the engine when pressing the Engine Start/Stop button. 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.
Smart key approval: When pressing the Engine Start/Stop button or depressing the brake pedal without
Smart key inserted into the key slot, SKM communicate with the Smart key to check if it has valid crypto
code. If it is valid, the engine can be started.
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Front temp. sensor
(11) 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
Rear temp. sensorCDPF (DOC+DPF)
Throttle valveD20DTF ECUDifferential pres.
sensorOxygen sensor