My headlights go out at different times at night, high beams still work. next time lights work fine .doesnt happen every night might go a month or so

is there a headlight raising /lowering switch inside the vehicle , these are very common and are usually a wheel type switch or a turn type ,both have numbers on them , 1 low -4or5 high , the owners manual should confirm if this is a component fitted to you vehicle

Try the relays for the high / low beams. It should be in the main fuse box. Next is a problem with the column switch.

Ok good luck

Have you checked to see if the bulbs are burnt out or if the low beam fuses are Blown?

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headlight relay or switch

Replace the switch. The low beam side of the switch isn't making a connection.

Most probable cause is your headlight switch, but could also be the headlight relay (in the underhood fuse box).

1999 GRAN PRIX SE HOW DO I INSTALL HEAD LIGHT BULB

Have you tried new bulbs, its rare but both low beams may have blown at the same time, it has happened to me in the past.
I don't know your car but the high and low beams could be fused separately so you are left with at least one set in an emergency.

possibly head lamp switch. daytime running lights on separate circuit and use the high beams at reduced voltage. does flash to pass work? that's high beams too. do high beams work?

Is it just low beams?
do taillights work?