(added to answer - There are 4 fusible links down at the starter. Check to make sure that they are all operable. If one is bad, it could be causing your power outage. Get a Haynes manual. They have excellent wiring diagrams in the back.)
It probably is the high/ low beam switch (in the steering column).
The headlights are a separate circuit from the others. Check the bulbs, headlight switch, Hi/Low beam switch and depending what year you have check the fuses.
Check for bad ground
a bad multi function switch or the wrong bulbs.gmjim
headlights
On my 89 there is a ground wire on the body in front of battery. Bad connection will cause problem with headlights. Could be hi/lo dimmer switch under dash. Hard to replace without removing steering column but I unplugged switch, plugged in new switch, set new switch on dim lights, and wired new switch to steering column so I have lights but only dim lights
Check to see if the dash lights dim or if the tail lights come on when the light switch is turned on. If these other lights work then check for a headlight relay. Most likely causes are either the switch or the relay.
The ground ciruit for the headlights is by way of the headlight switch , the lights always have power
have the alternator checked. u are drawing to much current when using lights, is usually a good indication that alternator is about to fail its not the altinater its new
It is probably the running lights that are working and the regular headlights aren't working because of the switch or wiring. TAke it to a garage.
It shouldnt. The cruise control senses by the switch on the pedal not by the lights.
The instruments light dim for night driving when the headlights are turned on. Check to insure that your dash dimmer switch is on high. If it is, then you have a problem with either the dimmer switch or the wiring.
check the multi function switch. I hava a 96 Chevy Monte Carlo and I had the same problem . I changed the multi function switch and the brakes lights now work. the rear brake lights run thru the switch on the turn signal circuit. try it and see.