Motorcycle Questions? Ask a Mechanic.
Hi Rodney and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, proposed preliminary checks (if have not been done) is to re-inspect the battery, its ground lines and/or check/clean the battery cables + terminals, connectors and wiring as a preliminary consideration. Have the battery externally charged and then LOAD TESTed (even if new/charged and just for the purpose of eliminating it as a suspect).
Let's work on the basics 1 at a time; (1) ensure good ground path. For test purposes, temporarily hardwire a secondary ground wire from the battery's - terminal to the frame, then also to the engine and then to several black wires of the harness including the headlight's.
With ensured good ground, test for the presence and consistency of +12V on ALL red wires and white wires.
There is a 24-pin connector that may be suspect and the above proposed test would help determine the likely culprit.
Perhaps an alternate approach to your concern would be to your preference.
The question would be re-opened as I would rather opt out.
Still, good luck with the ST2