I don't know about Fiat, but most GM and Cadillac have the same system. GM will need a match between the radio PIN and the computer pin + few maths algorithm, if both match, then you're in business... unless it will just write.. RADIO LOCK. And there's no way to bypass it with a numeric code.. you need to match EEPROM and computer. Most cutomer/used car dealer will go to the dealer... If you decide to buy a radio from a junk yard to change your own, just exchange the EEPROM, and enjoy!
As most radio decoding process, you need 1 working, one not working and few/many hours/days to discover how to make it work. I do GM now.
For FIAT, i can't tell, but maybe you could talk with one of my contact on your side.
http://www.davidsonelectronics.co.uk/
If the unit is made by Blaupunkt, it shouldn't be a big problem.
Audi need a numeric code only once, but if you transfer it into another car, he will prompt for a code... which can be read using some test point in the bottom of the radio. Same thing for most new VolksWagen.
Audioguru said:
Yeah, there are a lot of stolen car radios in Montreal.
Stolen or not, most of my customer a Used Car Dealers and Junk-Yard. Many buyed their used car from USA, and when they ask for USA code it may takes days/week before having it... while they have it the same day with me.
Also, the Dealer database is not 100% bug free. Worst are BMW, Mercedes, VolksWagen. Weird eh?