ooops, Now I remember, Thats almost the same as One I had last year, Ours turned out to be a faulty drivers door module, Reading up about the fault, It does cause a battery drain but everything can still work in single wire mode.

Knowing that fault code was present would have jogged my memory.

Jon Morgan suggested the right course of action.

>>>> Did you carry out a full diagnostic systems scan before you started?

Any faults logged anywhere that may have given you a pointer in which direction to look? <<<<<