I have a 1990 chevy truck the wiring got messed up so how do i run my headlights to stay on directly to turn on and stay on direvtly
The best way, pay someone that knows what they are doing to fix it.
I’ve seen to many cars burned to the ground because of people trying to fix the wiring on a car that have no clue as to what they are doing.
Only other option might be to find a truck just like yours in a auto recycling yard and get the complete harness, and replace yours.
For the base style headlamps there should be a light green, tan, and black wire going to the bulb. Placing battery voltage between the tan and black or the light green and black should light the headlamp. Black is the chassis ground. The correct and safe way is to find out what’s preventing that from happening using the headlight control switch, but a auto-electric knowledgeable mechanic could figure out a fused work around I expect, installing a separate set of switches to control the headlights. Definitely not a diye’r job for those without auto-electrical experience.