I wrote a reply this morning, but the iPad crashed as usual and didn't post it...
Sorry it's all so confusing to explain... This is going to be long... "Yes" and "No" or "doesn't matter" is the short answer but that's no help... Maybe that's what you meant by "silly question"?
Which ECU do you want to connect to? Presumably both engine and airbag ECUs, but hopefully not the ABS ECU, because I haven't seen anyone successfully connect to that. I'd like to connect to my Spider roof ECU, too, but I don't think the software exists to do that. Likewise I don't think there is software for the climate-control ECU in your GTV, or for the factory-fit alarm ECU. Theoretically the FIAT Examiner system (at your friendly dealer) can connect to all of these ECUs.
For a phase-2 like my 2000 Spider with 16-pin diagnostic connector in the fusebox, you just need your PC laptop and the usual translucent-blue OBD KKL cable, which also comes with a copy of VAG-COM that you don't need. I buy these cables from 'mediasave' on eBay, all my friends want them
here's the link: http://www.ebay.co.uk/itm/VAG-COM-US...ht_2862wt_1276
However, to connect to the airbag ECU, you'll need to connect pin 3 to pin 7. To connect to the ABS ECU, you'll need to connect pin 7 to pin 1, but it probably won't work due to software problems.
As for OBD2 and the engine ECU, your car has the red injector light, so it won't be OBD2 compliant, and a handheld OBD2 code reader won't work. The phase-3 GTV/Spider presumably has a yellow engine-outline light and is OBD2 compliant, which means a handheld code reader can read standard codes. That applies to 147s and 156s made after 2002, anyway.
The KKL cable on the other hand may be marked OBD or OBD2, it doesn't matter - it's the software that makes the difference. As you probably know, the main choices are Alfadiag, or FIATECUScan, which are a good investment as they allow you to do all sorts of things and connect to other ECUs (such as 156 Selespeed) that a handheld code reader couldn't do anyway.
Meanwhile, my '98 Spider is a phase-1, so it has the three-pin connectors in various places, and these need an adaptor (available from Hong Kong, on eBay) as well as the blue cable. I didn't know that a '98 could be a phase-2.
Hopefully that's cleared it up for you?