SsangYong Korando III (2010 year). Manual — part 583

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3) Supply Voltage Monitoring

The air bag unit monitors the battery voltage continuously while the ignition is turned on.. It limits certain

functions of the air bag system and outputs DTC and air bag warning lamp signal according to the result

of the monitoring.

Abnormal voltage of the air bag unit (too high/too low) is determined to be fault only when the signal

is detected for continuous 4 seconds.

Emergency power function

The SDM has an emergency power function that ensures the internal operation of the central unit

and buffering firing circuits for a minimum of 150 ms after loss of battery power. Full emergency

power capability is available after the minimum specified operating voltage has been applied to the

SDM power line for 10 seconds, and from this point, air bag deployment and EDR are enabled.

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4) Internal monitoring

The air bag unit checks the status of the air bag system and monitors the system for internal errors. If

an error is detected by self diagnosis, this unit disables part of the air bag system functions and outputs

a diagnostic trouble code (DTC) and air bag warning lamp signal.

Watchdog

The micro controller is monitored periodically. And if a fault is found, micro controller is reset, inflator

ignition function is limited, and the air bag warning lamp comes on.

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Air bag operations for errors

▶

Internal errors

Air bag operation

Front air bag system

Side air bag system

X-axis acceleration sensor

error

Disabled

Disabled

Y-axis acceleration sensor

error

Disabled

Z-axis acceleration sensor

error

available

ROM checksum error

Disabled

RAM checksum error

Disabled

NVM checksum error

Disabled

Internal acceleration sensor test

The air bag unit checks internal acceleration sensor when the ignition is turned on. The air bag unit

determines the deployment of the air bag for the collision signal input after the diagnosis.

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Non-volatile memory (NVM) test

The air bag unit checks the values stored in the memory. If the values are not correct, the air bag unit

sets a diagnostic trouble code (DTC) and turns on the air bag warning lamp.

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5) External monitoring

The air bag unit supplies a certain level of test current and monitors the resistance of the inflator circuit

within a specified range to deploy the air bag. It limits certain functions of the air bag, sets a DTC and

turns on the air bag warning lamp according to the conditions.

Inflator circuit resistance monitoring

▶

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Impact sensor monitoring

▶

The air bag unit supplies a certain level of test current to monitor the front and side impact sensors. If the

wiring is open/short circuited or no signal is input, or communication is malfunctioning, it sets a DTC and

turns on the air bag warning lamp.

Faults

Detection

Time for clearing

Fault condition

Time for detecting

Normal errors

Incorrect ID after IGN ON

Approx. 1 seconds.

Approx. 2 seconds.

(next Ign)

Faulty sensor after IGN ON

Communication error

Incorrect ID

Inconsistent ID after IGN ON

Communication

error

Communication data error

Approx. 2 seconds.

Open/Short circuit (B+)

Short Circuit to

Ground

Short Circuit to Ground

approx. 2 to 4

seconds

6) DTC and Air Bag Deployment Data Storing

DTC storing

▶

Airbag deployment data storing

▶

The DTCs realated to “low battery voltage" are not accumulated.

The air bag deployment data due to a collision cannot be cleared. The air bag unit should be

replaced.

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All DTCs of air bag system are stored in the air bag unit. Maximum number of DTCs that can be stored

is 16. If a new DTC is set after 16 DTCs are stored, the oldest stored code is erased first.

The air bag deployment data is stored in the air bat unit. Maximum number of data that can be stored is

7.