If you were going to do it that way, you would need to measure resistance at set values, eg for engine temp sensor...resistance at set values - then plot a graph, would determine whether they are linear or not, or if they have a positive or negative temp co efficient.
I still need more time to play with this, but you are right - decoding the protocol is the hardest - shifting the levels i have proved to work, so that is not a problem.
The problem is.....Alfa like to be different to ALL the other manufacturers - they ahave different packet size & baud rate to the norm. Typical. Bloody typical...
Websites are like ********s, everyone has one, and im wary of any bloke trying to direct people into their's