Head light s only lite on high beams

I DON'T KNOW. $1000 ASSEMBLIES ARE PROFIT MAKERS FOR DEALERS. I THINK ASSEMBLIES ARE JUST PLASTIC LIGHT SHADES AND NOT RELATED.
VISUALLY COMPARE PART NUMBER OR LOOK OF OLD BULBS WITH NEW BULBS. CHECK WITH CAR MANUAL.
WHAT IF THE LIGHT SWITCH OR RELAYS ARE FAULTY.?
AT NIGHT LOOK AT RUNNING LIGHTS. HAVE SOMEONE TURN ON LOW BEAMS.THEN HIGH BEAMS TO BE SURE.
YOU HAVE 3 LIGHT LEVELS. YOUR RUNNING LIGHTS AND HIGH BEAMS ARE WORKING BUT NOT YOUR LOW BEAMS. LOOK IN YOUR OWNERS MANUAL FOR THE HEAD LIGHT FUSES AND OR RELAYS TO SEE IF THERE ARE SEPARATE ONES FOR HIGH AND LOW BEAMS.

Hi Ricky, Im AL the owner of Big As Auto Repair.

Ricky, if the high beams work when you hold the lever in, then its the high beam switch NOT the light switch. The lever controls the high and low beams. You need the multi-function switch which is also the dimmer switch. Hope this helps and please visit my auto-repair-website at: http://www.bigasautorepair.com/

On the 1999 model, you have a relay for high and low beam circuits, and those relays send power thru a fuse for each side. The relays and fuses are in the fuse box in the engine compartment.
Check your owners manual for details.

check your head light relay and some models use a lighting control module LCM

You should have a low beam relay that powers the fuse for each side. If both sides are out chances are the relay is at fault. The relay and fuses should be in the fuse box near the battery.
Check your owners manual for details.

You may need a shop manual to fix this.
The headlight switch circuit involves high beam and low beam relays, and a fuse for each circuit, and the body computer controls it all.
You would need to know if the low beam fuses have power and the low beam relay is working.

Assume you're referring to 'low beams' not working? and 'high beams' are? Both circuits run they're own relays and fuses, check owners manual for locations, could be faulty relay (check by swapping with high beam relay) or blown fuse. Also find occasionally, both globes blown, high and low beam filaments in same globe

There may be a relay that operates the low beam lights, check the owners manual to see if there is a relay, you should be able to hear it go "click" if there is one.

Sometimes a ground will make the lights dim, if it is dim on one side look for the ground for that side. I had a little trouble understanding your Q. Try looking in your owners manual for location of relays

low beams are for foggy situations.. there should be a button to turn on the fog lights ... unless it has a sensor