The functions of the Fiat CODE unit are:

1- Recognize that has been placed and turned a key in the switch boot.
2- Issuing an electromagnetic field to give food and activate TRANSPONDER (transmitter code) of the key.
3- Receive the secret code emitted by the key. Save up to 8 Electronic keys with corresponding codes.
4- Direct controls / elaborations codes.
5- Conducting a serial bi-directional communication with a single cable to the engine control unit or DDS.
6- Direct ignition of a specific witness, recognize the connection to the Scanner and, in some versions, predispose the serial line for the function diagnosis.
1 – 2 – 3 – 4 – 5 Recognition of keys and unlock the motor.
The Fiat CODE system allows operation of the control unit engine through an exchange of codes.
When the key is in position UP (+15 = Contact) switchboard asks the engine control unit code to FIAT CODE latter
responds and sends a secret code only after recognized antenna through the electronic key is entered in the switch
Boot. Once recognized the code, the engine control unit allows to Start the engine.

The engine control unit as already seen, you can save the secret code only through a specific procedure.
When the ignition key to the RUN (+15) position, the engine control unit asks the code to the Fiat CODE unit and once it has received it, the compared with the main code (Master Code) memorized. If the comparison the code is positive, the engine control unit allows commissioning gait and normal engine operation.
In case of failure of the Fiat CODE control unit, the engine control unit activates the procedure of implementation of the emergency or Scanner well (in versions gasoline injection control / power integrated in versions with electronic control Diesel injection) using the accelerator pedal.

NOTES: It is prohibited to carry out exchanges of control switchboards between vehicles engine to check its operation. If placed the ECU of a vehicle without immobilizer if it has one, placing the Contact immobilizer code is recorded in the second ECU vehicle and will not allow the first engine start. This situation is IRREVERSIBLE.
If you must make a check of this kind (replacement ECU checking) with an ECU unscheduled (a vehicle without immobilizer or new) ECU, disconnect the connectors of the electronic central before placing immobilizer ECU testing. Failure to do so cause permanent lock control unit, leaving unused for other vehicles.
The main function of the Fiat CODE unit is the recognition of keys which are inserted into the ignition switch. The Fiat unit CODE, at the request of the engine control unit, sends you:
“The main code (recognized key), allowing the implementation and motor operation.
“The diagnosis code (unrecognized key) preventing commissioning engine running.
The Fiat CODE unit must also:
Save or re-memorize the keys. Memorize the main code (Master Code) in the engine control unit (if requested).
6 – Direct the CODE warning.
There are two procedures that allow dialogue between the PBX Fiat CODE and engine control unit.
When the Fiat CODE unit has memorized the keys, start dialogue
with the engine control unit that is still virgin. Exchange
information (memorizing the code) between the control unit
Motor and Fiat CODE unit is intended solely for the exchange of
engine control; Fiat CODE control unit can only answer
Questions engine control unit.

The control code is a standard procedure that is repeated every time the user places the electronic key into the ignition switch and turn RUN position (+15), the control procedure continues when rotated the key to START (+ 50). With the key in position UP (+15), the Fiat CODE unit must to recognize the dongle with its code; There are two possibilities:
a) If the Fiat CODE control unit recognizes the code, the control unit Engine allows engine operation (the CODE turns off)
b) If the Fiat CODE unit does not recognize the code, it will send a code to the engine control unit, which will not allow operation of the motor (the CODE warning light illuminates with fixed).

It will continue in next post…

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