Yeah, I fell foul of this. My airbag light is on so I went and bought the whole kit & caboodle, switched lead (then realised I have a 3-pin car!), bought a 3-pin adaptor, got FiatEcuScan software and plugged it to the airbag connector.
Unfortunately: If you have a Phase 1 GTV with an older TRW airbag unit (60625181 or 60664500 - mine is the 60625181) then FiatEcuScan (and also Alfadiag) won't see the ECU. Seems you have to have the MY97 airbag ECU.
Is there no software out there that will recognise the earlier airbag ECUs? Anyone?