@rogerrug
I can see that you're a very new member here at LZ, one post about insurance and the rest regarding your current troubles around the relay R9 and possible engine ECU problems.
As has already been said, our very senior member sierrafery is a very helpful bloke, especially when it comes to the electronics on the D2 Td5. Please remember that English is not his first language, so his written replies might not always be what could be regarded as "free flowing" but he's usually correct in his diagnosis. Stick around and you'll soon get to know who to ask about what subject, and nobody charges for their time and help.
Many of the circuits on the D2 are quite simple, battery, fuse, switch, load then earth but there are quite a few which are extremely complicated and take quite a bit of effort to sort out consequently as much information about a fault is often required. In some cases somebody might say, "Oh, yes. that happened to me and this is what I did to fix it" but more often than not we'll work from the electrical circuit diagrams and "first principles".
I gave you a drawing of the engine compartment fuse board which holds most of the relays, but to work out what you had said I would have had to go out in the street and open up my Disco to get some idea of exactly which relay you were talking about.
Right, and so to your problem. The relay R9 is called the "Main relay" and it's triggered from the engine ECU and the switched circuit feeds directly back to the ECU. That being the case, at this point even I, an ex-electronics engineer will defer to
@sierrafery at this point since he has very much more experience with that unit than me.