Brief Description of TWICE
Brief description of TWICE
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:
- Central locking system
- Immobilizer
- Anti-theft alarm
- Lamp check
- Heated rear seat
- Seat belt warning
- Electrically adjustable passenger seat
Central locking system
The car is fitted with central locking 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.
The remote control has three buttons for operation: lock, unlock and unlock tailgate.
The lock mechanisms and motors are integrated into one unit. The driver's door lock unit contains a microswitch which is activated by the key in the door lock.
The central locking 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.
Immobilizer
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 transponder.
On the ignition switch is a receiver which receives the identification code from the transponder and passes this to TWICE. TWICE has been programmed to recognize the car's transponders and if the key in the ignition switch is correct, the car can be started.
When any component in the immobilization chain is changed, the control unit must be reprogrammed.
Anti-theft alarm
The car can be factory-fitted with an anti-theft alarm, of which there are two variants:
- Variant 1 consists of: door switches, bonnet switch, luggage compartment switch and glass break sensor.
- Variant 2: as above plus an angle sensor (tilt sensor) which trips the alarm if an attempt is made to steal the wheels.
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 wheel housing. The behavior of the alarm when tripped is market- dependent and programmable.
Lamp check
TWICE checks the circuits for the rear lights and brake lights.
- Rear lights
TWICE acts as a filament monitor for the rear lights. On a break in a circuit, SID can read an error message on the bus sent out by TWICE. The message activates an information text on the display or 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 an error message on the bus sent out by TWICE. The message activates an information text on the display or 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 Trionic and TCM.
Heated rear seat
The car can be factory-fitted with heated rear seats, two heating pads are then mounted in the outer two seats.
TWICE controls the connection time for the heating as a function of the outside temperature.
Seat belt warning
The seat belt warning lamp always lights for 6 seconds when the ignition is turned 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 according to the load on the seat.
Electrically adjustable passenger seat
TWICE controls a relay which is connected in series to the electrically adjustable 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. With the ignition in the ST position, no operation can be carried out.
P-bus and I-bus
In the Saab 9-5, all the car's control modules are connected to buses with the exception of the ABS and SRS control modules.
The buses are divided into the Powertrain bus (P-bus) and the Instrument bus (I-bus) Both buses are connected to the main instrument unit (MIU). The buses are electrically isolated from each other. The P-bus has a data transfer rate ten times higher than that of the I-bus.
All information sent out by a control module is available to all other control modules connected to the bus. The MIU ensures that the information which is available on one bus is also available on the other.