I spent several hours trying to connect to my phase-1 '98 Spider's Airbag ECU with no success at all - even KWP71 failed to connect (also tried Alfadiag, FIATEcuScan, and a program I hadn't heard of before: AlfaOBD.) All of these successfully connected to my engine ECU, proving that the cable/serial port settings were working.
I realised during all of this that I had accidentally been plugging in to the Roof ECU diagnostics connector which is kind of near the airbag ECU on the Spider
The airbag diagnostics connector is on a short yellow lead, attached to the metal lid over the airbag ECU, which by the way has part number 60625181 on mine. Naturally I tried everything again... A Google search showed this particular ECU has caused others grief in the past, so no real surprise that I've wasted hours. The next stop will be an Alfa specialist with a couple of Alfa-specific scantools, and after that, someone with a FIAT Examiner.
The real surprise of the day: AlfaOBD
Obviously I can't take any credit for this and I'm sure many of you have found this years ago, but I was unaware of it.
This easy-to-use software actually connected to my Spider's Roof ECU - something I don't recall ever knowing anyone had done. It was easy - just choose Alfa Spider, and Rear doors/Boot/Hood, connect with a OBD/KKL cable and 3-pin adaptor, and click Connect.
The screenshot below shows that I have a few faults - the main one being that lock switch which explains the erratic behaviour where the locks release, but then the back of the hood doesn't raise unless I help it by hand.
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It's a great feeling to think that I can see into its little brain and find out what's troubling it. Hopefully this is the start of a deep and meaningful relationship with my Roof ECU, and I hope that perhaps this might help someone else trying to figure out why the roof switch fails to respond or work correctly (and when it isn't the famous plastic gear in the cover release motor).
A joy for another day will be using AlfaOBD to connect to the Climate Control ECU in my phase-2 Spider (it's on the list), though I will need to work out what pin of the OBD (16-pin) connector that is. I'm sure I saw that information somewhere... EDIT: turns out it's in the Help for AlfaOBD.