Austin Deuning

I know the harness, headlight relay and grounds are 25 years old

Where would I find the grounds?

My turn signals stop working when the headlights turn on and the indicators in the cluster illuminate solid. What could be the main issue? I’ve replaced bulbs and LCM. im not sure if it could be the harness, grounds or headlight relay

I recently replaced the light control module on my 1999 Chevy Silverado 1500 but now the left turn signal emits a buzz when activated and it slightly flashes when the right turn signal is activated. prior to changing it the right turn signal buzzed and the indicator on the cluster would stay on (but not flashing)