Process of elimination.
If the headlights flash on and off, there may be a problem with the bulbs or fuses. There may also be a problem with the battery connections or wiring.
1. You have a busted headlights. 2. You have a busted fuse for the headlight. 3. Have an Electrical wiring connection problem. 4. No battery charge
There is no fuse between the headlights and the battery. If the headlights are dead, then your problem comes down to: battery (may have some voltage, but no current) and the battery cables.
I'm not a mechanic / technician but if your battery is overcharging or the headlights are too bright so people are flashing their headlights at you when you are just using low beams ( it sounds like a voltage regulator problem )
Sounds like the battery went dead or you have loose/dirty battery connections.
Because the power for your headlights is pulled from your battery. When the dashboard lights dim after turning on the headlights the dashboard lights aren't getting as much power as they were with the headlights off. With the motor running or off? The headlights draw a lot of current, but should not visibly affect other systems. There could be a problem with a worn out battery, an alternator that isn't charging correctly, or you have a bad earth between the battery and the chassis. Check the large cable connection between the battery (usually negative these days) and the bodywork, or between the engine block and the bodywork.
Sounds like an electrical problem, check your battery, alternator, and fuse box, and light wiring.
Problem with the charging system. Altenator, Battery, etc.. (may even be a loose belt causing the alternator not to spin fast enough to charge the battery).
check your fuses. that is the most likely cause. My son had the same problem with a 1998 sonata. Fuses were fine. Apparently, the wire bundle carrying the wire for the headlights was pinched between the battery and the fuse box under the hood. His battery holder wasn't holding the battery tight and it moved towards this wire and pinched it. Once that wiring bundle was moved above the battery, then the headlights worked!
command start malfunction, disconnect, problem solved.
it is caused by the alternator voltage regulator switching on and off to charge the battery, this problem is encountered on many makes of car, you may not of noticed it before prior to exchanging the battery.
Sounds like your alternator and battery need to be replaced soon.