3022536 - 5580E anti-theft device

SPECIFCATIONS

The cars are equipped with an electronic system known as the ALFA CODE that acts as an engine immobiliser.The ALFA CODE system allows the engine to start by means of the Engine NCM only after receiving a secret code memorised previously.

SPECIFIC FEATURES OF THE SYSTEM

The second generation Code system is integrated in the Body Computer Node (NBC).

COMPOSITION

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

  • C CAN line for dialogue with BCN and ECN
  • bidirectional serial line for recovery ( W line)
  • two to eight electronic keys containing a transponder with a secret code;
  • an aerial which reads the code contained in the key transponders;
  • the NCM for petrol engines and for electronic diesel pumps or the Diesel Valve Electronic Driver (D._E.D.)
1 - NBC 2 - ECN 3 - Aerial 4 - Key

OPERATION

INTRODUCTION

The ALFA 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 NCM 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 ALFA CODE function is also guaranteed in the case of malfunction of the other NBC functions.After recognising an enabled transponder, the ALFA CODE switches off any alarm system.

INTERACTION OF ALFA CODE WITH THE KEY

Each key contains a transponder with the IDENTIFIER CODE and the SECRET CODE.As soon as the ignition is switched on (+15), the transponder sends the identifier to the ALFA CODE which, recognising it as one of the enabled ones, proceeds with the strategy for recognising the cytographic transponderIf the identifier is not recognised, the procedure aborts, preventing the engine from being started.The cryptographic transponder 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 ALFA CODE attempts for 1 second to acquire the transponder.

DIALOGUE BETWEEN ENGINE CONTROL NODE AND ALFA CODE

The dialogue between ALFA CODE (NBC) and NCM takes place on the C-CAN under normal operating conditions. Each exchange of information between ALFA CODE and the NCM (the ALFA CODE never interrogates the NCM, but only answers after a request from the latter).When the ignition is switched on, the flow of operations involving code exchange between the ALFA CODE and the NCM depends on the state (virgin or memorised) of the engine management control unit.If the NCM is virgin, the procedure involves the fix code request to the ALFA 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 ALFA 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 on 2 - NCM initialisation 3 - Memorized/virgin NCM status 4 - Memorization successfully completed ? 5 - ENABLE ENGINE MANAGEMENT = the flow of software continues with the management of the engine management. 6 - PROHIBIT ENGINE MANAGEMENT = activates a timer which creates a dely to only enable a new procedure after 0 - 600 secs. It is necessary to remove and and restore +15. If a timer is not available (with + 30) it will be necessary to wait 0 - 600 secs in key on. After this it is possible to carry out a new procedure with a KEY OFF and KEY ON. 7 - Is the secret code valid ? 8 - SEE POINT 6 9 - SEE POINT 5 A - CODE VERIFY B - CODE RECORDING

Code recording

The 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 ALFA 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 ALFA 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 ALFA CODE does not respond.When the ALFA CODE is virgin and there is no transponder in the aerial and a a FIX code request is sent from the NCM to the ALFA CODE, the ALFA CODE does not respond.

Code verify

This 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 +50 (CRANKING).After the key is on KEY ON (+15), the ALFA 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 NCM 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 ALFA CODE.In response to this request, the ALFA CODE will send the fix code, encrypted by the Minikrypt, to the engine management control unit, only if the transponder has been recognised as enabled.If the ALFA CODE receives further (FIX code) requests, it only reads the transponder in the aerial again before responding to the NCM if there are visible signs of possible manipulation (see later).If the result of the transponder recognition is negative (incorrect transponder, no transponder in the aerial, etc.), the ALFA CODE will send the code (incorrect transponder or no transponder) to the engine management control unit.If the ALFA CODE is virgin and the NCM sends a FIX code request, the ALFA CODE, after recognising a transponder, responds by sending an encrypted virgin NBC recognised transponder code, encrypted by the Minikrypt.

METHOD OF USING C-CAN OR RECOVERY W LINE

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

  • C-CAN faulty
  • 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 NCM passes on to recovery from the accelerator pedal or the diagnostic instrument.
The recovery strategy is mainly managed by the NCM, which acts as a master unit during communication: the NBC acts as the slave unit and must therefore always be ready to respond to code requests from the C-CAN and W serial line.

Communication on c-can

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

  • IMMO CODE REQUEST (immo code request)
  • IMMO CODE RESPONSE (immo code response)
The IMMO CODE REQUEST is sent by the NMC and received by the NBC.The IMMO CODE RESPONSE is sent by the NBC and received by the NCM.

Communication on w line

If, 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, the IMMO CODE REQUEST and the IMMO CODE RESPONSE.

VERIFYING W LINE ELECTRICAL CONNECTION

As 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 ALFA CODE function is implemented via the exchange of secret codes between the various subsystems (keys, NBC, engine management unit).UNIVERSAL CODE: this is the code which the ALFA CODE, not yet programmed, sends to the NCM when it has recognised the presence of a transponder in the key.The ALFA CODE 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 ALFA 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 ALFA CODE at the time of programming the keys at the end of the line.FIX CODE: This is memorised in the ALFA 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 NBC 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 ALFA CODE during the programming procedure. The ALFA CODE manages a table of enabled identifications and one for disabled identifications.

DESCRIPTION OF THE COMPONENTS

ALFA CODE FUNCTION IN THE NBC

Specifications

The ALFA CODE on the 147 is a function of the BCN

The main functions of the ALFA CODE are:

  • to recognise the introduction and rotation of a key in the ignition switch (+15);
  • to de-activate the alarm 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 C-CAN line to the engine management control unit;
  • to manage the lighting up of the warning light on the panel by dialoguing with the NQS;
  • to carry out self-diagnosis.

Aerial

Characteristics

Toroidal aerialOhm value= 40 Ohm

Composition

The aerial assembly consists of a 131 coil toroidal reel aerial with built-in connector on the aerial body.The connecting wiring to the BCN is integrated in the dashboard wiring loom.

Operation

The aerial is supplied by the NBC 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 aerial 2 - Ignition switch

IGNITION KEY

Characteristics

The mechanical key contains a cryptographic transponder in the handle.

Operation

When the key is inserted in the switch and the ignition is switched on (+15), 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 ALFA 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 ALFA 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. following the procedures in the 'REPAIR PROCEDURES' section.
1 - Transponder

KEY TRANSPONDER

Specifcations

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.

Key programming

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