184000375 - 5580E ANTI-THEFT DEVICE

CODE SYSTEM

The anti-theft device consists of the CODE system which immobilizes the engine.
The complete alarm system, including perimeter protection, volumetric protection and anti-tilt protection is not available on this model as an optional extra, but is available through ''Linea accessori''..
OVERALL VIEW
1 - Body Computer (NBC)2 - Engine Management Control Unit (NCM)3 - Aerial4 - Key

SPECIFCATIONS

For the engine immobilizer function, the cars are fitted with an electronic system called FIAT CODE II.The FIAT CODE system allows the engine to start by means of the Engine Mangagement Node (hereafter called NCM) only after receiving a secret code memorised previously.

COMPOSITION

The FIAT CODE system comprises 5 basic elements (in addition to the Body Computer which acts as the main control unit):

  • CAN line for dialogue with the NBC and NCM
  • bidirectional serial line for recovery ( W line)
  • electronic keys containing a Transponder with a secret code;
  • an aerial which reads the code contained in the key transponders;
  • engine management control unit (NCM)

OPERATION

Introduction

The FIAT CODE allows engine control management to be commenced by the NCM by coded dialogue between the NBC and NCM during the pre-starting stage.After the ignition is switched on, the NCM sends a request code to the NBC which responds only after recognizing (via the aerial) a known electronic key inserted in the ignition switch. If the secret code contained in the response is valid, the ECM continues with the usual engine control activity, allowing the engine to be started.The NCM can memorise the secret code only by means of a particular procedure.The FIAT CODE function is also guaranteed in the case of malfunction of the other NBC functions.

Interaction between fiat code and key

Each key contains a transponder with the IDENTIFIER CODE and the SECRET CODE.As soon as the ignition is switched ON, the transponder sends the FIAT CODE identifier to the NBC which, recognising it as one of the enabled ones, proceeds with the strategy for recognising the SECRET CODE.If the identifier is not recognised, the procedure aborts, preventing the engine from being started.The SECRET CODE is recognised by means of a challenge-response algorithm with exchange of encrypted code.The code recognition time does not exceed 160 ms per attempt.The FIAT CODE attempts for 1 second to acquire the transponder in any case.

Dialogue between engine control node and fiat code

The dialogue between the FIAT CODE (NBC) and NCM control units is implemented via the CAN in normal operating conditions.Each exchange of information between the FIAT CODE and the NCM is guided by the NCM (the FIAT CODE never interrogates the NCM but only responds after a request).When the ignition is switched on, the flow of operations involving code exchange between FIAT CODE and NCM depends on the state (virgin or memorised) of the NCM.If the NCM is virgin, the procedure involves the fix code request to the FIAT CODE: in this way, the NCM learns and memorises the secret code. This procedure is called CODE RECORDING.If the NCM is programmed, the procedure involves checking that the fix code memorised in the engine control unit is the same as that memorised in the FIAT CODE (NBC): the NCM asks the NBC for the secret code and compares it with its own. This procedure is called CODE VERIFY
1 - Key on2 - NCM initialisation3 - Memorised ECN state OK, virgin OKAT CODE VERIFY7 is the code valid?8 engine operation is permitted9 engine operation is not permittedB CODE RECORDING (code memorisation)4 memorisation completed correctly?5 engine operation is permitted6 engine operation is not permittedCode recordingThe CODE RECORDING procedure is the memorisation of the fix code in the engine control unit.Only after memorising the identifiers, secret code and fix code, the FIAT CODE is ready to meet the request to transmit a code from the NCM which is still virgin.After ''power on'', the engine control unit initialises its software and, if it is virgin, asks for the fix code.If the FIAT CODE is not virgin, it will respond by sending the fix code, but only after recognising an enabled key. If it is a disabled (unknown) key or there is no key, the FIAT CODE does not respond.If the FIAT CODE is virgin and there is no transponder in the key and a fix code request is sent from the NCM, the FIAT CODE does not respond.Code verifyThis is the standard procedure which is repeated during the life the car whenever the driver inserts the key in the ignition switch and turns the ignition on (+15) (= KEY ON): this procedure allows engine starting if the inserted key is enabled.The code verify procedure continues even wne the driver turns the key to the AVV position (CRANKING).After the key is on KEY ON, the FIAT CODE recognises whether the transponder in the key is one of the enabled ones.At the same time, with the key on +15 or +50, the ECN initialises its software to verify whether a fix code has already been memorised. If it has, it will send a (FIX code request) to the FIAT CODE.In response to this request, the FIAT CODE will send the fix code, encrypted, to the engine control unit, only if the transponder has been recognised as enabled.If the FIAT CODE receives further FIX code requests, it again reads the transponder in the aerial before responding to the NCM.If the result of the transponder recognition is negative (incorrect transponder, no transponder in the key, etc.), the FIAT CODE will send the code (incorrect transponder or no transponder) to the engine control unit.If the FIAT CODE is virgin and the NCM sends a FIX code request, the FIAT CODE, after recognising a transponder, responds by sending an encrypted virgin NBC recognised transponder code.

Method of using c-can or recovery w line

Communication between the BCN and ECN takes place by default on the C-CAN line; if the C-CAN network is faulty, the recovery strategy is as follows:

  • the ECN passes on to recovery on the W serial line, requesting the code from the BCN: if the outcome is positive, starting is permitted
  • if there are also problems on the W line, after re-transmission attempts, the ECN passes on to recovery from the accelerator pedal or the diagnostic instrument.
The recovery strategy is main managed by the ECN which acts as master in the communication: the BCN, which has to respond to code requests coming from both the C-CAN network and the W serial line.Can communication

The communication between Body Computer and NCM is achieved by the following two CAN messages:

  • Immo code request (sent from NCM and received by NBC)
  • Immo code response (sent from NBC and received by NCM)
Communication on w lineIf, because of a malfunction on the CAN network, you move on to the recovery condition, the exchange of codes between NCM and NBC takes place on the W serial line.This code exchange takes place only for the CODE VERIFY procedure: it is therefore not possible to carry out a CODE RECORDING on the W line.The data exchange on the serial line takes place in the same way as on the C-CAN network: the NCM control unit is master of the communication, while the NBC responds to the requests received from the NCM.Two messages travel on the serial line: immo code request and immo code responseVerifying w line electrical connectionAs the dialogue on the W line only takes place in the case of recovery, an ERROR condition would only be recognised at the time of use, so the end customer would not be able to move the car.A strategy of verifying the W serial line is therefore introduced in order to diagnose the line itself.

Protection codes

The protection codes used by BCN and ECN are given belowUNIVERSAL CODE: this is the code which the FIAT CODE, not yet programmed, sends to the NCM when it has recognised the presence of a transponder in the key.The ''vehicle protection'' warning light comes on at a frequency of 1.6 Hz and duty cycle of 50%.The flashing of the light explains that the system is correctly connected and working, but the car is not protected by a code.IMMO CODE: This is the basic code from which the secret code and fix code are obtained. An automatically generated immmo code is associated with each car. All the other secret codes used by the FIAT CODE function are generated from the IMMO CODE.SECRET CODE: This is the code resident in the transponder. It is memorised in the transponders contained in the car keys at the time of programming the transponders, and in the FIAT CODE at the time of programming the keys at the end of the line.FIX CODE: This is memorised in the FIAT CODE at the time of end-of-line programming.ELECTRONIC CODE (PIN): This is obtained from the fix code and is stamped on the CODE CARD which is delivered to the car''s owner; it is a 5-digit decimal code (0 is not permitted).It is used to access, in a protected manner, the BCN memory in order to re-programme or programme new remote control keys and/or carry out particular diagnostic functions.It is also used in the procedure of recovery from accelerator pedal described in the engine control unit specification.IDENTIFIER: It is resident in the transponder and is different for each transponder. It is memorised in the FIAT CODE during the programming procedure. The FIAT CODE manages a table of enabled identifications and one for disabled identifications.

DESCRIPTION OF THE COMPONENTS

Body computer

The FIAT CODE on the vehicle is a function of the NBC

The main functions of the FIAT CODE are:

  • to recognise the introduction and rotation of a key in the ignition switch (+15);
  • to de-activate the alarm (if fitted) after recognition of an enabled key;
  • to emit an electromagnetic field to read the key''s transponder;
  • to send the random code to the transponder;
  • to receive the cryptographic code emitted by the key;
  • to memorise up to 8 identifiers;
  • to memorise the secret code;
  • to manage a list of a maximum of 8 enabled identifiers;
  • to manage a list of at least 16 permanently disabled identifiers;
  • to manage the CAN line to the engine control unit;
  • to manage the lighting up of the warning light on the panel by communication with the instrument paenel;
  • to carry out self-diagnosis.
Supply of fiat code as sparesIn the case of replacement of the FIAT CODE, the entire Body Computer needs to be replaced.If the Body Computer is being replaced the Parts Dept. must be asked, using the V.O.R. procedure and supplying the vehicle chassis number, to provide an ''identical copy'' of the Body Computer: this copy will contain all the default settings entered for the vehicle when new which are stored in the Parts database for that chassis number.

Aerial

CompositionThe aerial assembly consists of a toroidal reel aerial with built-in connector on the aerial body.The connecting wiring to the BCN is integrated in the dashboard wiring loom.OperationThe aerial is supplied by the BCN to energise the key''s transponder.As the aerial needs to be as close as possible to the transponder (for electromagnetic immunity, its small size and the limited range of the transponder), it is attached axially to the ignition switch.
1 - CODE aerial2 - Ignition switch

Ignition key

OperationThe mechanical key contains a cryptographic transponder in the handle.When the key is inserted in the switch and the ignition is switched ON, the transponder is energized by the aerial and responds by emitting the secret code in a variable and encrypted way.The emission into the air has sufficient power to have high immunity to electromagnetic interference and a range such that it is received by the aerial mounted in the ignition switch.If the code is recognised as valid, the FIAT CODE sends the engine control unit, at the request of the latter, a coded signal that allows the engine to be started.Up to 8 keys can be programmed in the FIAT CODE.
The keys are supplied ''already programmed'' by the production factory. All the codes are then stored in a DATA BASE managed by the PARTS DIVISION. Therefore, when a new vehicle is handed over to a customer, the Service Network should not carry out any programming procedures. If a key is mislaid or additional keys are requested, this request should be passed on to the Parts Dept [PR5580E].
Key transponder

The transponder contained in the key has the following coded in its memory:

  • SECRET CODE, the same for each transponder in the same key kit;
  • IDENTIFIER, different for each transponder produced;
  • DATE OF PROGRAMMING the secret code.
The identifier differs from transponder to transponder to ensure that, even if duplicates are requested on the Network, there are not several transponders with the same identifier.Reprogramming the keysReprogramming the keys enables the keys authorised to start the car to be memorised in the NBC.If the new keys to be programmed and those already programmed will be inserted in the ignition switch to be recognised by the FIAT CODE which will memorise in the table of enabled identifiers those presented during the procedure, and will transfer from the latter table to the table of disabled identifiers those identifiers which have not been presented.Table of disabled keysIf an enabled key is no longer available (lost, stolen or no longer working), the subsequent key programming procedure (for example necessary for memorising the new replacement key) should disable its operation.The FIAT CODE therefore manages a table in EEPROM which can contain the data relating to 16 disabled keys: the identifiers of the enabled keys not presented during the reprogramming procedures are trans
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