If all this fails you can always remove the immobiliser from the system by making and fitting an immobiliser jumper plug, as detailed on page 66 of the M3W parts list Ver 5.2 item C-47 on the RH side. You will also need an AMP Multilock 070 12 way male plug and pin set. Morgan could supply these at one time but don't seem to be able to now. I got my plug from
www.simtekuk.co.uk and they were very helpful. With the jumper fitted the immobiliser is out of the system, handy for diagnosis as well as a small, light item to carry in your spares bag that may just come in useful one day?