The GEMS system is quite different and was fitted for a relatively short period in the V8's life. There is a lot of information on the GOMOG site where Lorne tackles it in some detail including scanning fault codes. I'd suggest you have a look there. Lorne is also very happy to answer questions directly and this I feel will be a good shortcut for setting you on the road of understanding.
The OP has a 5 speed Morgan three wheeler with S & S V twin engine. Its doesn't use OBD2 protocol.
