There are typically 2 filaments in your head light so you probably need to change out the bulbs. I'm not sure about your year but typically you can pull out the whole light assembly and when you get the lens off you can just change out the "brights" bulb. If you can't get the light apart you just need to change out the whole thing. It's $10 at auto zone.tbeasley said:I have a 1999 jeep cherokee and the headlights work perfect on dim but when you flip them on bright they turn completely off. I put a new dimmer switch in it and still the same thing. Any ideas on whats wrong?