SsangYong Actyon Sports II. Service manual - part 41

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2. SYSTEM OPERATION

1) Input/Output Diagram of Glow Plug Control Unit

2) System Diagram

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3) Circuit Diagram

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4) Operation

Glow plug is installed in the cylinder head. It enhances the cold starting performance and reduces the 

exhaust gas during cold starting.

ECU receives the data (engine rpm, coolant temperature, vehicle speed) through CAN lines. Based on 

the data, GCU controls the pre-glow, cranking and post-glow. It also checks the glow plugs, and sends 

the result to ECU.

(1) Temperature/Current Properties of GCU

GCU increases the temperature of glow plug very rapidly (approx. 2 seconds up to 100

FETs (similar to transistor) for each cylinder are integrated in GCU. During the pre-glow 

period, battery voltage is supplied to the glow plugs directly to heat them rapidly.

After getting the desired temperature by pre-glowing, the temperature is controlled by duty 

ratio.

Step 1:

Step 2 & 3: 

Step 4:

This shows the supplying voltage and time by GCU in each step. The step 4 is the period to keep the 

temperature.  

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Step 1: I1

Step 2: I2

Step 3: I3

Step 4: I4

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(2) Pre-heating time control based on battery voltage

GCU monitors the battery voltage. If it is low, GCU extends the pre-heating time.

GCU monitors the energy to glow plugs (the amount of pre-heating energy is always same).

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GCU monitors the battery voltage. If it is low, GCU extends the pre-heating time to get enough 

energy.

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GCU monitors the battery voltage. If it is low, GCU increases PWM duty..

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