Fiat CODE control unit

When the ignition is switched ON (+15), the engine control unit requests a code from the Fiat CODE control unit; after receiving the code, it compares it with the Master Code stored in memory. If the comparison of the code gives a positive result, the engine control unit permits starting and normal operation of the engine.

If the Fiat CODE control unit is faulty, the engine control unit manages the emergency starting procedure activated by the Fiat Lancia Tester or (for petrol versions with integrated fuel injection/ignition systems and diesel versions with electronic fuel injection) by means of the accelerator pedal.

Under no circumstances may engine control units be exchanged between cars to check whether they are working.

During diagnosis, before replacing the engine control unit, make sure that the component under examination really is faulty, because when the new engine control unit is supplied, the Master Code will be memorized, rendering it entirely unusable on other cars.

Fiat CODE control unit

The main function of the Fiat CODE is to recognize the keys inserted in the ignition switch.

At the request of the engine control unit, the Fiat CODE unit sends to the former:

• the Master Code (key recognized), enabling starting and normal operation of the engine;
• the diagnosis code (key not recognized) preventing engine starting.

The Fiat CODE control unit also has to do the following:

• manage the memorization or rememorization of the keys;
• memorize the Master Code in the engine control unit (at the request of the engine control unit);
• manage the CODE warning light.

There are two procedures for dialogue between the Fiat CODE control unit and the engine control unit:

1. after the Fiat CODE control unit has memorized the keys, dialogue with the UNUSED engine control unit begins. The exchange of information (registration of the code) between the engine control unit and the Fiat CODE control unit is guided only by the engine control unit; the Fiat CODE control unit is only enabled to respond to interrogations from the engine control unit;
2. checking the code is a standard procedure which is repeated whenever the user inserts the electronic key in the ignition switch block and turns it to the ON (+15) position; the checking procedure also continues when the user moves the key to the START (+50) position.

With the key at the ON (+15) position, the Fiat CODE control unit must recognize the electronic key with its relevant code. There will be two possibilities:

• recognition of the code by the Fiat CODE control unit; the engine code control unit enables starting and engine operation (the CODE warning light goes out);
• if the code recognition is negative, the Fiat CODE control unit will send a code to the engine control unit which will not permit engine starting (CODE warning light is on permanently).