Quote Originally Posted by shaunyprawn View Post
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A brand new ignition relay shows a consistent resistence of 77.6Ω across it, but the ignition relay in at the moment was showing anything - literally! It jumped around from 3 to 20, whereas the new relay stood at a constant 77.6. This would explain the varying current to the J59 relay and the ignition failures.
Swapping this relay out seems to have done the trick so fingers-crossed, it should be sorted once and for all.