Hi to all! I´m Kai from Finland and me and my step dad are working to make an OBD system for 1970´s Chrysler vehicles. The company itself made one during the era and we would like to have same kind of system, only with 2010 equipment. (so no fridge- size computer for my shop) We´ve solved most of the continuity and voltage measurements, but there are a few tacks we are fighting with. First problem is the ampere metering for starter motor: it should be able to test amperes from range 0 to 700 for cranking current evaluation and alternator output. I know there are shunts to be used in parallel with the ampere meter but they seem to have very limited ampere suppression. Second question is that we need to get multiple information on one wire: there are only 7 wires on the OBD port for 50-60 different functions. What can be done to separate multiple analog signals from one wire? Most of the components being tested have separate grounding circuits if that helps anything. I´ve heard of multiplexing but don´t know if there´s and easier way to get into same result. We were thinking of using a PC board in series between the OBD port and the laptop. I do the schematics and building and my step dad does the programming for the system diagnostics but neither of us is an electric engineer so I thought this might be the place for help. Thank you for reading and hope to hear from you!