by Warkton Tornado No.1 » Sun Jun 21, 2020 12:10 am
If you know that the electrical system is drawing constant current, you presumably have access to a meter of some type. In which case, you can disconnect individually each connection to the loom, starting with the headset, because the horn is most likely, as has been suggested. Set correctly, your meter should change values, hopefully to zero, with any bad component. So whilst in the headset, check them all if the horn is not @ fault.
Probably, the next likely culprit is the brake light circuit, especially the foot switch. The brake light circuit also has a permanent live supply as with the horn.