have you checked your fuses? it could be as simple as that This is true, there is a separate fuse for the high beams, low beams and radio. Fuses for 1999 LHS are located behind a side panel (drivers side) of the dash next to the steering column. Driver's side door must be open and there is a wiring diagram on this panel.
check the fuse
anti theft system is bad
pulsars
I had a similar problem with a '70's model pontiac. There had been an aftermarket stereo installed and believe it or not the + and - were backwards (radio was wired backwards) Only difference was if I had the radio on and turned the high beams on it blew the radio fuse. Hope this helps you.
I just had this same problem with my 1998 VW Jetta. My parking brake light came on one day, but only half illuminated. Shortly after my windshield wipers and headlights stopped working. My radio works but the fans don't work either. I just found a thread which seems to point the problem at the ignition switch: http://car.justanswer.com/volkswagen/6uht-1998-volkswagen-jetta-headlights
If you turn up your interior dashboard light settings, then the radio display will be brighter too. The radio dims to the setting for the dashboard when the lights are turned on.
Often when a car radio in not working a blown fuse is the culprit. It also could be a wiring problem or a defective radio.
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.
I think it is a dying battery
The radio display is usually tied to the dash board lights. As you raise or lower the illumination on the dash, the radio lights should change. During the day (with your headlights off), the radio display is at full brightness so it is easier to read in daylight.
I had the same problem behind your stereo there is a yellow wire whit a yellow-white wire they have to touch each other otherwise the low beams wont work.. i hope this wil work..Relay K behind the ash tray. Check the socket also.AlThis is the answer! We burned out the yellow white wire to the dimmer switch hooking up a radio. Reran that wire and hooked it up to the yellow white wire and now we have low beams. High beams would work (if you held in on the arm, parking lights worked, but not the low beams. Replaced the k fuse (after a 4 day wait) and still nothing. Tried this and it worked!-Thank you:-)
The headlights probably have a bad ground. the alternator is probably going bad.