For 1990-2009 cars

### Tasks

The intelligent switching unit (ISU) is the car-body control unit, which realizes some functions as actuators controls, vehicle access controls, or alarm functions.

The Immobilizer function is shared between the ISU and the engine control module (ECM) control units.

The Immobilizer tasks of the ISU are:

• | Communication with the key transponder after the ignition ON transition (identification and authentication of the key, learning of the keys)

• | Communication with the ECM control unit after the ignition ON transition (receipt of the ECM request and transmission of release message)

• | Control of the immobilizer status indicator (LED)

• | Communication with the diagnosis tester , such as keys learning, diagnostic

### Immobilizer Function

The immobilizer function of the ISU control unit has 3 main modes:

• | The Immobilizer Active mode--Selected when the ignition key is OFF. In this mode, the status indicator LED is driven in mode A or B. Cranking is not possible.

• | The Nominal mode--Selected when the ignition key is switched ON and the Nominal mode condition is verified. It is the current mode of use. In this mode, 2 function states are considered:

- | Blocked state--In this state, the vehicle should be immobilized. Cranking is not possible.

- | Released state--In this state, the vehicle can be mobilized. Cranking is possible.

• | The Learning mode--Selected when the ignition key is switched ON and the Learning mode condition is verified.

Because conventional electrical systems have a separate circuit for each system for things such as, simple timers, relays and individual control units, they require a lot of components as well as complex wiring.

The ISU integrates these complex units and wiring into a micro-controller that controls itself intelligently.

By doing that, the number of components is smaller and the wiring simpler; in addition, the diagnosis of electrical system problems is also made easier using the scan tool.

### Defogger

The power source is IGN 2. If you press the defogger switch to ON, the rear glass and ORVM defoggers operate for 15 +/- 3 minutes, automatically. If you press the switch once again, or turn OFF the IGN 2 power while the defoggers are operating automatically, then the defoggers will turn OFF.

### Central Door Locking (Default Operation)

If you press the LOCK/UNLOCK buttons of the door locking switches on the driver or front passenger door, all 4 doors will lock/unlock all at once.

If you use the key or knob on the driver door to lock/unlock the doors, all 4 doors will lock/unlock all at once.

If you press the LOCK/UNLOCK buttons on the transmitter while the ignition key is out of the ignition cylinder, all 4 doors will lock/unlock all at once. In this case, according to the condition, the theft deterrent system goes into an armed or disarmed mode.

The door locking actuator operates for about 0.2 seconds.

### Key Reminder Warning

If the driver door is opened with the IGN ON and the key reminder switch ON, the internal buzzer of the intelligent switching unit (ISU) will operate.

If you remove the ignition key from the key cylinder or turn the IGN ON while the buzzer is operating, the buzzer will turn OFF.

### Light Warning

The light warning system has 2 modes, armed or disarmed.

When you open the driver door with the light ON (system armed) the buzzer will operate.

If the driver door is closed, or if the light switch is turned OFF while the buzzer is operating (system disarmed), the buzzer will turn OFF.

### Seat Belt Warning

When you turn the ignition ON with the driver seat belt unbuckled, and the seat belt switch ON, the buzzer will operate for 6+/- 1 seconds.

If you buckle up the driver seat belt, with the seat belt switch OFF, or turn the ignition OFF within 6 +/- 1 seconds, the buzzer will go OFF.

Because the seat belt warning lamp is not controlled by the intelligent switching unit (ISU), but is directly controlled by the seat belt switch, the lamp stays ON as long as the seat belt is unbuckled.

### Turn Lamp and Hazard Lamp

The power source of the turn lamp is IGN 1 and the power source of the hazard lamp is B+.

If one of the turn lamps malfunction, other turn lamps on that side will blink 2 times faster than they normally do. Normal is 85 Hz, but the side turn signal lamp is not affected.

### Power Window

When the intelligent switching unit (ISU) receives IGN 2 power, the power window relay is grounded by the ISU. When the power window relay is energized, the main driver power window switch, and the motorized ORVM supply operational power to the driver power window switch which has 2 modes, first mode, manual UP/DOWN, and second mode, automatic UP/DOWN.

The power window motor halts automatically in case the motor current reaches 85 percent of the initial starting current while in the UP or DOWN auto mode.

The power window motor also halts automatically in case the switch is pressed to ON again while in the UP or DOWN auto mode.

### Wiper

The wiper can operate when IGN 1 power is supplied.

When the INT signal of the wiper switch is supplied to the intelligent switching unit (ISU), the internal relay of the ISU is energized for 0.5 seconds, and the wiper motor will start to move. After 0.5 seconds, the motor will operate just one cycle and will stop at the parking position by the cam plate switch circuit of the wiper motor.

Intermittent time can be adjusted from 1.5 seconds through 12 seconds by the intermittent time adjusting switch.

If the washer switch input time is more than 0.3 second, the internal wiper relay of the ISU will energize. The wiper motor will continue to work while the washer switch is in ON. If the washer switch is turned to OFF again, then the motor will cycle 2 more times.

### Interior Lamp

When the interior lamp switch is positioned in the middle or in the door position, the intelligent switching unit (ISU) will control the interior lamps.

If one of the 4 doors is opened while IGN 1 power is OFF, the interior lamps will come ON; however, after 15 minutes have passed, the interior lamps will go OFF automatically in order to prevent battery discharge.

The interior lamps, will turn ON automatically when a door is opened with IGN 1 OFF, then the lamps will stay ON for 7 +/- 0.1 seconds until the doors are closed again, and for 2 +/- 0.5 seconds thereafter. The lamps will slowly dim for 7 seconds and then finally go OFF.

With IGN 1 ON, interior lamps are turned ON only while the doors are opened. The dimming function is disabled.

### Key Halo Lamp

If the driver door is opened while IGN 1 power is OFF, the key halo lamp will come ON. It will stay ON for 8 +/- 0.1 seconds even though the driver door is closed.

Because the key halo lamp is disabled during IGN 1 ON, if IGN 1 is turned ON within the delay time, 7-9 seconds, the lamp will go OFF.

### Remote Trunk Release

If you press the trunk button on the transmitter with the key reminder OFF, the trunk actuator will operate for 0.3 +/- 0.03 second; However, if in the middle of the theft deterrent alarm, it will stop.

If the trunk button is pressed with the trunk open, the actuator will not operate.

### Theft Deterrent System

The transmitter is integrated in the ignition key and its battery is replaceable. The key code consists of a FIXED code and a ROLLING code.

The theft deterrent system can be operated only by using the transmitter. If you open the doors, the hood or the trunk not using the transmitter or the ignition key, or if you turn the ignition ON, while in armed mode, the theft deterrent alarm and the hazard lamp will operate for 28 seconds.

#### Remote Central Door Locking

If you press the LOCK/UNLOCK button on the transmitter while in a theft deterrent armed condition, the central door locking operates according to the following chart:

• | One of the 4 doors is opened.

• | The trunk is opened.

• | The hood is opened.

If you press a button on the transmitter while one of the above 3 conditions is met, the theft deterrent system will not work, but the central door locking will operate.

However, if the door locking actuator is operated using the transmitter while the driver door is open, then the driver door is not LOCKED, because UNLOCK will only operate mechanically using the driver door knob S/W, after LOCK operation.

If you press the LOCK/UNLOCK button on the transmitter while in a theft deterrent armed condition, the central door locking will continue to operate.