2001 Pontiac Grand Prix headlights

Are you saying the headlamp switch doesn't work? If so, check the headlamp circuit breaker in the fuse box, check for voltage on the circuit. At the headlamp switch, orange wire is hot all the time. When you turn on the headlamp switch, the yellow wire carries voltage to the dimmer switch.

the headlights works ,it only goes off sometimes .it usually doesn't work at night ,basically it turns on and goes off on it own

All I can do is check the wiring circuits when the problem occurs.