Used ECU kits should contain both the engine computer and the body computer, and a full set of keys and locks. Once fitted, the car effectively becomes the donors identity.
That works as long as the donor is of the same spec, or a higher spec, as you can disable features if they're not fitted, but a lesser ECU may not have them programmed to be able to be enabled.
If you fit a kit intended for a Punto, it will effectively become a Punto. There will be questions to be answered.
Is the kit, BOTH ECUs? If not, it is unlikely that your body computer will properly talk to the Punto engine computer. But it might, if it is just a basic engine management unit, although we do not know how it will take the immobiliser information, as both ECUs need to agree before accepting a key.
To operate the doorlocks, I'd guess you'd need a Punto 5-door ECU, but do they send the same signals to the van door locks?
Even if the ECU plugs are the same, so will plug in, have Fiat used the same pins for the same purposes? This could be difficult to determine, unless you are willing to pore over wiring diagrams for both and compare every connection and wiring route. Fiat might use different colour wires on the different vehicles, for the same purpose. Fiat are not known for consistency.
There are probably lots more compatibility issues, these are just off my head quickly.
After spending hours studying wiring diagrams, it might all work, so if you have time, good luck with the homework. Or if the price is right, you could just plug and play, and see what occurs. Couold be exciting, or a can of worms. Take care.
