Body Function Controller (BFC)

The Theft Deterrent System's logic is contained within the Body Function Controller (BFC). The BFC will read Passlock Cylinder Data from the Passlock (TM) Lock Cylinder within a certain timing window. If the Passlock Cylinder Data is correct and within the timed window, the BFC will Pass Theft and will transmit it's coded password to the Powertrain Control Module (PCM). There are two ways the BFC may enter a theft mode;
^ A bad timing cycle
^ Bad Passlock Cylinder Data

If the Passlock Cylinder Data is not read within the timed window, the Vehicle Theft Deterrent will go into a Short Tamper Mode during which the PCM will not allow the car to operate for 4 seconds and the BFC will send a Serial Peripheral Interface (SPI) serial data message to the Instrument Cluster and the THEFT SYSTEM indicator will flash. After 3 consecutive failed timings, the Vehicle Theft Deterrent (VTD) will go into it's Long Tamper Mode. In this mode, the BFC will send a SPI serial data message to the Instrument Cluster and the THEFT SYSTEM indicator will flash. The Fuel Injectors will be disabled for approximately 10 minutes.

Important
^ Please note, before any Tamper Mode the vehicle may start; however, the car will quickly stall. If the BFC receives the wrong Passlock Data, the VTD will immediately go into it's Long Tamper Mode in which the vehicle's fuel injectors will be locked-out for 10 minutes as described above.
^ The THEFT SYSTEM indicator will flash while the VTD is in any Tamper Mode. The BFC continually checks the operation of the VTD during the operation of the vehicle. If the THEFT SYSTEM indicator lights continuously during vehicle operation, refer to the System Diagnosis.