On my Citroen Relay they are orangey red/green, white/green, and black
But I have learned you can't assume anything about the wiring colours on a Sevel van
When I needed to find the Alternator D+ I looked at the converters guide and it shows it as a brown/white wire going to the converters socket.
My X2/90 Ducato van has this socket, even though it is not on the spec sheet or been charged for.
I tried to find it at the loom going in but couldn't
So took the socket out and found it was brown/black
I found a brown/black wire in the loom nearer where I wanted it, and cut that to find it wasn't the D+
I then found another brown/black wire and cut that to find it wasn't the D+ either
So I had to go back to the converters socket and cut the brown/black wire there to wire it in and run a cable back from there.
I can only guess the loom manufacturer must have run out of some colours, and substituted whatever other colour came to hand