2. Immobilization

Fig 1: Identifying Bus Function Chains (Immobilization)

Courtesy of SAAB-SCANIA OF AMERICA, INC.

When the ignition is turned on. TWICE checks that the right key is inserted in the ignition switch. A circuit built into the remote control part of the key sends a code by means of inductance to a coil round the ignition switch under the center console. The code is passed on to the control module which checks that it is correct. TWICE also checks that the right MIU is fitted in the car. MIU continuously sends out an ID number on the bus.

If the key and the MIU's ID number are OK, TWICE sends out the message "Immobilization OFF" on the bus. This information is used by Trionic which cancels fuel shut-off, which is always activated every time the ignition is switched on.