ABS light is on and no self test by ECM 1990 xjs V12

Hello, i’m new on this forum. My name is Conrad and i live in Belgium.
I have a 1991 xjs v12 and have some problems with the ABS system.
Contact on : loc light is on and not bright light, red brake light is not on.
Look to pull error code with connecting the black with the Braun/pink wire in de red connector and it is not working, the anti lock licht stay the same and nothing is happening.
some info, the pump is working as it should , enough fluid in reservoir.
when disconnecting plug from pressure switch and fluid reservoir the red light is on with contact on and stay on with engine on idle .( as it should)
i anyone have this problem before?
Thank u for reading, Conrad.