Are you sure you have the headlights wired correctly? If you switched the ground and the high beam wires at the terminal, the headlights would still work (may be a bit dim) and could cause the condition you are seeing. If this was the case, when you switched to the low beams, the lights would still work and mixed up ground would back feed the high beam indicator to make it light, thus would be on all the time the headlights were on.
Last edited by Phak1; 02/11/2021 1:09 AM.