Japowa

Hello all! I am looking to reset my ABS light after a bad ground on the abs unit that is sorted now. The ABS is still on not really sure why but that's not the main problem. When I wire the diagnostic socket with a pin, the horn goes off! Wtf? I took of the horn fuse and tried and the duagnistic doesn't work at all. Does anyone know what the problem could be?
Setup:
Stock B18C swapped Ek4 with a chipped and socketed P28 that was fully refurbished and tuned by a professionnal.