Ok so I replaced the alternator on my 1984 90 200tdi as the battery wasn't charging (new battery) and still not charging so traced all the wires using a wiring diagram I have 3 wires big brown wire, white wire and a yellow wire. I think the brown wire is wrong as its earthed and in my diagram it shows the brown wire linked up to the starter motor solenoid but when I do that I have no electrics and the truck won't turn over! What am I doing wrong?

yelow one is actually brown and yellow.

brown goes to b+
brown/yellow goes to d+
you don't have a tacho on your 90 do you? else i'd guess white goes to W. but white on a landy is also an ign live, so be careful
earth is via casing.

and if a previous owner has mucked about with it, then it could all be anything

Thanks for that il sort that then an hopefuls it should work but there has been a concise table amount of buttering of wires from previous owners I need to contend with ahaha