XJ6R – Major step forward!
I have just turned the engine over using the original S2 ignition switch! That might not sound much but what it actually means is that the Security and Control Module, the Body Processor, the Exciter/Reader, the XJR key, the ECU and a few switches and relays have all agreed that it is OK to turn the engine over. The engine immobiliser circuit is accepting the new setup.
Overjoyed at this moment. Still a huge journey ahead but a major hurdle overcome.
I did paste a little update on the Jaguar forum but I will paste a full explanation later as I want to check out a few other things.