Forgot to say
with brown plug removed, there is 130ohms on the engine side and 120 ohms on the cab side.
Coming back to think about immobiliser?
Key chip looks fine, unfortunately I haven’t got a spare key to try. The tel tale red led in the roof panel is blinking as normal, not sure if this should change if ignition is turned on or key in? Is there any way of testing or bypassing immobilser? I can see immobiliser with Delphi but have no ability to check key coding etc.