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Brief description, anti-theft alarm

Brief description, anti-theft alarm


The theft protection on the car consists of two different functions, the immobiliser which is standard on all cars, and the anti-theft alarm which is an option. The theft protection functions are controlled by TWICE.

Immobilization

The immobiliser prevents the car starting if the wrong key is used. The fuel supply is shut off and the starter motor relay blocked. The car key contains a transponder with a unique identification code which is received by a receiver unit. The receiver is located in the ignition lock.

The receiver, which is connected to TWICE, sends the code to TWICE which is programmed to recognize the car keys. If the right key is inserted in the ignition (ignition position ON), the engine can be started. If a faulty transponder or one which does not belong to the car is used, “KEY NOT ACCEPTED” appears on the SID display.

In the event of a fault on the receiver unit or transponder, the remote control can be used instead to mobilise the car. The car can be mobilised by pressing a button on the remote control after the ignition key has been turned to the ON position.

Anti-theft alarm

The anti-theft alarm can be factory-fitted or installed as an accessory.

The anti-theft alarm is armed/disarmed with the remote control. Arming/disarming can also be carried out with the key in the driver's door or boot lid/tailgate (disarming) on the US/CA/LA markets. If the anti-theft alarm is armed and the key is turned in the ignition switch, the anti-theft alarm will be disarmed once the transponder has received the correct identification code.

The anti-theft alarm has the following inputs for tripping the alarm:


• Door switches

• Luggage compartment switch

• Bonnet switch

• Ignition lock (position ON with incorrect key)

• Glass breakage sensor

• Tilt sensor (accessory)


A tripped alarm is indicated by:


• Direction indicators

• Siren


The behaviour of the anti-theft alarm depends on the market.

Door switches

The door switches are mounted in the frame of the door concerned and grounded through the switch mounting screw to the bodywork. The switches are supplied with a pulse width-modulated (approx. 3.5%) voltage via a 1 kohm pull-up in TWICE. When a door is opened, the switch is closed and the control module input is grounded.

TWICE sends out information on the door position to the bus, where it is used by DICE for example for interior lighting. The anti-theft alarm also uses the door switch.

Luggage compartment switch

The luggage compartment switch is fitted in the boot lid/tailgate lock. The switch is powered by a pulse width modulated (approx. 3.5%) voltage via a 1 kohm pull-up in TWICE. If the luggage compartment is opened, the switch will close and ground the control module input.

TWICE sends the position of the boot lid/tailgate to the bus and this information is used by DICE for the luggage compartment lighting. The anti-theft alarm also uses this switch.

Key switch luggage compartment disarming

The key switch is mounted by the boot lid/tailgate and grounded through the switch via the body. The switch is powered by a pulse width modulated (approx. 3.5%) voltage via a 1 kohm pull-up in TWICE. If the key is turned in the switch, the switch closes and grounds the control module input. The boot lid/tailgate is disarmed.

Bonnet switch

The bonnet switch is placed at the rear left of the engine bay. The switch is supplied with a pulse width-modulated (approx. 3.5%) voltage via a 1 kohm pull-up in TWICE. When the bonnet is opened, the switch is closed and the control module input is grounded.

TWICE uses the bonnet switch to trip the anti-theft alarm if the bonnet is opened when the alarm is armed.

Glass breakage sensor (4D)

The glass breakage sensor is located in the rear roof light and is powered from TWICE.

The glass breakage sensor reacts to the sound of breaking glass. The sensor is of the active type and makes its own assessment and decision on whether the glass has been broken.

The sensor can be disconnected by pressing the NIGHT PANEL button on SID when the car key is not in the ignition switch.

Glass breakage sensor (5D)

There are 2 glass breakage sensors in the 5D, front and rear. The front is active and located in the centre roof lamp. The rear is passive and is located in the luggage compartment roof lamp. The front one is the main sensor and is connected directly to TWICE, while the rear one is a slave sensor and is only connected to the main sensor.

The glass breakage sensor react to the sound of breaking glass. The front sensor, which is active, assesses the situation and determines whether glass has been broken.

The sensors can be disconnected by pressing the NIGHT PANEL button on SID when the car key is not in the ignition switch.

Tilt sensor

The tilt sensor is placed under the right front seat and is powered from TWICE.

The sensor reacts to the car's angle and sets off the alarm if the car is raised on one side, just before the wheel is lifted off the ground.

It does not react for example if the car is buffeted by a strong wind. The sensor should however be disconnected if the car is to be transported on a ship as the anti-theft alarm may trip.

The sensor can be disconnected by pressing NIGHT PANEL on SID when the car key is not in the ignition switch

Siren

The siren is placed on the front edge of the front left wheel housing. The siren has two piezo-electric sound emitters and is equipped with batteries so that it can sound in the event of a power failure from the car's ordinary battery or if someone cuts the leads to the siren.

Direction indicators

The car's direction indicators are activated via bus information from TWICE which DICE uses to turn on the direction indicators.

LED (Light Emitting Diode)

The LED is placed on the top of the dashboard and is powered from TWICE.

The LED is used to indicate the status of the anti-theft alarm:


- A double flash means that the car is immobilised.

- A flash every 3 seconds means that the anti-theft alarm is armed.

- A fast flash during the delay time means that a door or the bonnet or tailgate is open.

- A continuous light during the delay time means that everything is OK.


Remote control

The remote control is used to operate the central locking and to arm and disarm the anti-theft alarm.

The remote control is fitted with three buttons which have the following function:


• Lock/arm anti-theft alarm

• Unlock/disarm anti-theft alarm

• Unlocking the boot lid/tailgate and disarming the boot lid/tailgate alarm


When a button on the remote control is pressed, a code is sent to a receiver. The receiver is connected to TWICE which performs the required command.

P bus and I bus


All the control modules in the Saab 9-5 are connected to the buses except those for the ABS and SRS.

The two powertrain systems, Trionic and TCM, are not connected to the I bus, however. These systems need much faster communication facilities so that no delays will be noticeable, such as in connection with torque limitation when changing gear.

The Trionic and TCM are therefore connected by means of a separate bus called the P bus (Powertrain Bus). The communication speed (data transfer rate) of the P bus is ten times faster than that of the I bus.

In addition, the P bus is connected to the MIU. The MIU ensures that information which is available on one bus is also available on the other.

The diagnostic instrument is not connected directly to the bus but communicates via the DICE, one of the control modules connected to the I bus, and so has access to all control modules connected to the bus.

Vehicle speed is an important item of information for many control modules. Since the ABS is not connected to a bus, the vehicle speed signal goes to the MIU via a cable of its own. The MIU then sends out the vehicle speed information on the buses.