SsangYong Korando III (2010 year). Manual - part 59

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4) System 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 various signals such as engine rpm, coolant temperature and vehicle speed through 

CAN communication lines. GCU controls the pre-heating, cranking and post-heating operations and 

monitors the glow plug. If GCU detects a problem, it sends the result to ECU.

(2) Operation of AQGS

Duty control area: 

Between 5 and 100%

Frequency: 20 Hz
Duty ratio = (RMS voltage)²
                   (Battery voltage)²

1.

2.

3.

(1) Characteristics of temperature and current in AQGS

AQGS unit increases the glow plug temperature very rapidly (1,000˚C in 2 seconds).

FET (similar to transistor) for each cylinder in AQGS unit pre-heats the glow plug.

If the glow plug temperature reaches to target temperature, the temperature is controlled by 

duty ratio.

1.

2.

3.

AQGS PWM Control

Actual voltage pattern

AQGS unit supplies the power to glow plug.

This shows the voltage and time 

supplied by AQGS by steps. As shown 

on the graph, the supplied voltage is 

decreased as the steps are continued. 

The 3rd step is to keep the temperature, 

not to raise it.

Frequency: 20~33Hz

PWM Control duty ratio

- 1st step: 100%

- 2nd step: 35%

- 3rd step: 23%

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(3) Operating Steps

Pre-Glow: Step 1

▶

If normal communication with the ECU is established 2 seconds after the power is supplied to the IGN 

terminal from the battery, the GCU supplies the battery power to raise the temperature of the glow plug 
to 1000℃ by the preheating request from the engine ECU before starting.

- The time for pre-heating is controlled by the ECU.

If the input voltage (VB) is 11.5 V or less, GCU supplies the battery voltage for preheating time (T1).

If the input voltage (VB) is greater than 11.5 V, GCU supplies the voltage of 11.5 V for preheating time 

(T1).

-

-

The preheating time may vary according to the conditions.

Input voltage 

VB (V)

Pre-heating time T1 

(sec)

6 8.27 

7 5.8 

8 4.1 

9 3.15 

10 2.4 

11 1.95 

≥ 11.5 

1.9 

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During cranking: Step 2 and step 3

▶

Step 2: If the ECU receives the cranking signal after pre-heating (step 1), the GCU supplies the 
voltage of 6.8 V for 1 sec to raise the temperature to 1,100℃.
Step 3: The GCU supplies the voltage of 5.1 V to keep the temperature at 1,000°C.

1.

2.

Under fixed temperature: The AQGS unit supplies power for 30 seconds (Step 1 + Step 3) if no 

cranking signal is received after the step 1.

During cranking: The step 3 is started after the step 2.

*

*

Post-glow: Step 4:

▶

The post-heating is for reducing HC/CO after the engine is started. If the time for post-heating exceeds 

180 sec., the GCU unit cuts off the power to each glow plug even if there is preheating request from the 

engine ECU.

Emergency glow

▶

If no CAN signal is received for 4 seconds from the engine ECU after the IGN ON signal is input, the 

GCU performs emergency preheating (Step 3) for 30 seconds.

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Normal operating mode

▶

This shows the components of preheating system in the pre-heating and the post-heating steps.