Body Control Systems: Description and Operation

Intelligent Switching Unit Description

Intelligent Switching Unit (ISU)
Because the conventional electric systems, in which simple timers, relays and individual control units are used, have separate circuit for each system, they require a lot of components as well as complex wiring.
But ISU does not need such things because it integrates such complex units and wiring into a micro-controller and also controls itself intelligently.
By doing that, the number of components gets smaller and the wiring simpler, in addition, the diagnostics of electrical systems easier by using the scan tool.

Defogger
Power source is IGN2. If you press the defogger switch ON, the rear glass and ORVM defoggers operate for 15 ± 3 min. automatically. If you press the switch once again or turn OFF IGN 2 power while the defoggers are operating automatically, then the defoggers are turned OFF.

Central Door Locking (Default Operation)
If you press LOCK/UNLOCK buttons of the door locking switches on the driver or co-driver door, 4 doors are locked/unlocked all together.
If you lock/unlock by the key or knob of the driver door, 4 doors are locked/unlocked all together.
If you press LOCK/UNLOCK buttons of the transmitter while the ignition key is out of the ignition cylinder, 4 doors are locked/unlocked all together. In this case, according to its condition, the anti-theft system goes into armed or disarmed mode.
The door locking actuator operates for about 0.2 sec.

Key Reminder Warning
If the driver door is opened with IGN ON and Key reminder switch ON, Internal buzzer of ISU operates.
If you remove the ignition key from the key cylinder or turn IGN ON while the buzzer is operating, Buzzer goes OFF.

Light Warning
When you open the driver door with light ON (Light switch 1 or 2 step), Buzzer operates.
If the driver door is closed or the light switch is turned OFF while the buzzer is operating, it goes OFF.

Seat Belt Warning
When you turn the ignition ON with the driver seat belt unbuckled, (the seat belt switch ON) Buzzer operates for 6 ± 1 sec.
If you buckle up the driver seat belt (the seat belt switch OFF) or turn the ignition OFF within 6 ± 1 sec. since the buzzer operated, the buzzer goes OFF.
Because the seat belt warning lamp is not controlled by ISU but controlled directly by the seat belt switch, the lamp stays ON as long as the seat belt unbuckled.

Turn Lamp and Hazard Lamp
Power source of the turn lamp is IGN 1 and the hazard lamp's B+.
If one of the turn lamps malfunctions, other turn lamps of that side blink 2 times faster than normal one. (normal: 85 Hz) But the side turn signal lamp is not concerned.

Power Window
The power window relay is grounded by ISU when ISU receives IGN 2 power. When the power window relay is energized, the main switch of the driver power window and the motorized ORVM are supplied operation power to the driver power window switch of the main switch has 2 steps such as 1st step, manual UP/DOWN, and 2nd step, automatic UP/DOWN.
The power window motor halts automatically in case that the motor current reaches 85% of the initial starting current in auto mode UP/DOWN.
The power window motor halts automatically in case that the switch is pressed on again in auto mode UP/DOWN.

Wiper
The wiper can operate when IGN 1 power is supplied.
When the INT signal of the wiper switch is supplied to ISU, the internal relay of ISU is energized for 0.5 sec., and the wiper motor starts to move. After 0.5 sec., the motor operates just one cycle and stops at its parking position by the cam plate switch circuit of the wiper motor.
Intermittent time can be adjusted from 1.5 sec. through 12 sec. by the intermittent time adjusting switch.
If the washer switch input time is more than 0.3 sec., the internal wiper relay of ISU is energized. The wiper motor continue to work while the washer switch is ON. If the washer switch is turned OFF again, the motor cycles 2 times more.

Interior Lamp
When the interior lamp switch is positioned at the middle or the door position, ISU controls interior lamps.
If one of the 4 doors is opened while IGN 1 power is OFF, interior lamps come ON, But if 15 min. passes after interior lamps ON, they go OFF automatically in order to prevent battery discharged.
Interior lamps, turned ON automatically by opened door with IGN 1 OFF, stay ON for 7 ± 0.1 sec. even since doors are closed again, and for 2 ± 0.5 sec. after that 7 sec. slowly dimmed and finally go OFF.
With IGN 1 ON, interior lamps are turned ON only while doors opened. (Dimming function disabled)

Key Halo Lamp
If the driver door is opened while IGN 1 power is OFF, the key halo lamp comes ON. It stays ON for 8 ± 0.1 sec. even since the driver door is closed.
Because the key halo lamp is disabled during the IGN 1 ON. If IGN 1 is turned ON within the delay time, 8 ± 1 sec., it goes OFF.

Remote Trunk Release and Anti-Theft
Transmitter can control door lock/unlock, auto trunk open, anti-theft system.

Remote Trunk Release
If you press the trunk button of the transmitter with the key reminder OFF the trunk actuator operates for 0.3 ± 0.03 sec. But in the middle of anti-theft alarm stops.
If the trunk button is pressed with the trunk open, the actuator does not operate.

Anti-Theft System
The transmitter is integrated in the ignition key and its battery is replaceable.
Key code consists of FIX code and ROLLING code.
Anti-theft system operates by only the transmitter. If you open the doors, the hood and the trunk not using the transmitter or the ignition key, or if you turn the ignition ON, in armed mode, the siren and the hazard lamps operate for 28 sec.

Remote Central Door Locking
If you press LOCK/UNLOCK button of the transmitter in anti-theft armed condition, the central door locking operates as the following chart.
- One of the 4 doors is opened.
- The trunk is opened.
- The hood is opened.

Even if you press buttons of the transmitter while one of the above 3 conditions is met, anti-theft system does not work, and central door locking operates.
But, if the door locking actuator operates by the transmitter while the driver door is open, the driver door is not LOCKED, because UNLOCK operates mechanically by the driver door knob S/W after LOCK operation.
If you press LOCK/UNLOCK button of the transmitter in the anti-theft armed condition, the central door locking operates.