SAAB WIS ONLINE

Brief description of TWICE

Brief description of TWICE

General

TWICE stands for Theft Warning Integrated Central Electronics. The TWICE control module is located under the left-hand front seat, screwed to the floor, and connected to the wiring harness with a 70-pin connector.

Twice controls the following functions:


• Lamp check

• Seat belt warning

• Electric heated rear seat

• Electric powered passenger seat

• Central locking system

• Immobilization

• Anti-theft alarm


Lamp check

TWICE checks the circuits for rear light and brake lights.


• Rear lights


TWICE acts as a filament monitor for the rear lights. On a break in a circuit, SID can read en error message on the bus sent by TWICE. The message activates an information text on the display and an audible warning.

TWICE checks whether voltage is present at the rear light inputs; this information is available on the bus. The information is used by DICE.


• Brake lights


TWICE acts as a filament monitor for the brake lights. On a break in a circuit, SID can read en error message on the bus sent by TWICE. The message activates an information text on the display and an audible warning.

TWICE checks whether voltage is present at the brake light inputs; this information is available on the bus. The information is used by SID.

Seat belt warning

The seat belt warning light always lights for 6 seconds when the ignition is switched ON. If the belt tongue is pressed into the buckle, the lamp goes out after these 6 seconds; if not, the lamp stays on.

On certain markets there is also an audible warning which is activated if any passenger has not fastened their seat belt when the ignition is ON. The audible warning is active for 6 seconds when the ignition is turned ON or until all seat belts are fastened.

The passenger seat is fitted with a sensor which detects when the seat is occupied. The resistance of the sensor varies depending on the load on the seat.

Electric heated rear seat

The car can be factory-fitted with heated rear seats. Two heater pads are then fitted in the two outer seats.

TWICE controls the connection time for the heaters as a function of outside temperature.

Electric powered passenger seat

TWICE controls a relay which is connected in series with the electric powered passenger seat. When the relay is activated, the seat can be operated.

Operation is possible with the ignition ON or OFF with any front door open. With the door open and the ignition OFF, the function is turned off after 20 minutes.

Operation is possible during a period of 30 seconds after the driver's or passenger's door is closed or after the ignition is switched OFF.

With the ignition in the ST position, operation is not possible.

Central locking system

The car is fitted with a central locking system as standard and TWICE controls the motors. The central locking can be operated with the remote control, the key in the driver's door, or the switch on the centre console.

There are three buttons on the remote control for: locking, unlocking and unlocking the boot lid (4D) or tailgate (5D).

The lock mechanisms and motors are integrated into one unit. The driver's door lock unit contains a microswitch which is activated when the key is put into the door lock.

The central locking function has three positions: UNLOCKED, LOCKED, and THEFT SECURITY LOCKED. The latter means that the car CANNOT be unlocked from inside the passenger compartment. The theft security locking function is market dependent.

Immobilization

The car is fitted as standard with a system which prevents the car being started without the correct key. For this, a transponder is incorporated into the key with a code unique to that particular transponder.

On the ignition switch there is a receiver which receives the identification code from the transponder and passes this information on to TWICE. TWICE has been programmed to recognize the car's transponders and if the key in the ignition switch is one of the right ones, the car can be started.

When any component in the immobilization chain is changed, the control module must be reprogrammed in combination with the component.

Anti-theft alarm

The car can be factory-fitted with an anti-theft alarm, of which there are two variants:


• Variant 1 comprises; door switches, bonnet switch, boot lid/tailgate switch and glass breakage sensor (4D) or glass breakage sensors (5D).

• Variant 2 consists of; as above plus a tilt sensor which trips the alarm if an attempt is made to steal a wheel.


The anti-theft alarm has a piezo-electric siren. The siren has an integral battery to ensure that the alarm can be given even if the power from the car's ordinary battery (car battery) is interrupted. The siren is located at the front of the left-hand front wheel housing.

The behaviour of the alarm when tripped is market dependent and programmable.

P-bus and I-bus


All control modules in the Saab 9-5 are connected to the bus with the exception of ABS and SRS. For cars with Traction Control, the TC/ABS control module is connected to the bus.

The bus allows large quantities of data to be sent between the control modules on only two cables. The bus is divided into a Power train bus (P-bus) and an Instrument bus (I-bus).

Trionic, TCM and TC/ABS power train systems require fast data communication so that no noticeable delay occurs, e.g. for torque limitation when changing gears.

Trionic, TCM and TC/ABS are connected to the P-bus, on which data transfer is ten times faster than on the I-bus.

The P-bus and I-bus are connected to the MIU. The MIU is responsible for making information on one bus available to the other bus.

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 data is important for many control modules. Since the ABS is not connected to the bus, the vehicle speed signal is sent on a separate lead from the ABS to the MIU. The MIU then sends the data over the busses. In cars with Traction Control, the TC/ABS sends vehicle speed data to the MIU via the P-bus.