SsangYong Korando III (2010 year). Manual - part 373

15-37

0000-00

PTC heater

Coolant 

temp. sensor

D20DTF

ECU

Engine room relay box

HFM

(Intake air 

temp.)

(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

A: PTC 1 (changeable)

B: PTC 2,3 (not changeable)

15-38

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.
Operation process: reaches at a certain temperature→high resistance→low current→less heat 
radiation→temperature down→high resistance→high current→temperature up

15-39

0000-00

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)

▶

15-40

Meter 

cluster

Immobilizer 

antenna

Immobilizer key

Start motor

BCM

ECU

D20DTF

(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)

▶