bad light switch.
low beam fuse blown.
Possibly two bulbs, possibly the switch. Get it diagnosed. check your fuses for your headlights. i have a '97 accord and installed aftermarket headlights and one day one of my lowbeams wouldn't work but my high beams would be on with my low beams on, and when i switched for the highbeams, my low beams would both go out. you can get a thing at shucks, or even walmart, to check the fuse to see if it's working, very simple to use. :) Did you try replacing the one headlight that only works on the high beam mode? First check to see if you have a relay. If it dont have one, the problem lies on the dimmer switch. Locate the dimmer switch. On some vehicles the dimmer switch is part of your headlight switch. If only one of your headlights is affected then it probably isn't a fuse or relay. A light that is both a low beam and a high beam has two filaments. One of the filaments is probably broken. Replace the headlight and it should fix the problem. i did replace the lamp on a 96 sunfire and the low beam still does not function. highbeams work fine, but no low beams on both headlights now. I have a similar problem. Both headlights low beam filaments on my WRX STi had blown and the replacement low beam filaments blew too??? So I've still only got high beam which is fine but other drivers are getting a wee bit annoyed (and rightly so)All fuses are good and correct factory ampage. The new bulbs are H4's which is the factory correct bulbs yet low beam filaments gone on both bulbs. I'm bewildered...
Perhaps a beam balance is the subject of your enquiry? If so, a rider beam is the beam along which one moves the small pointers till the point of balance is reached. A Triple Beam Balance will have three such beams. Coarse, medium and fine.
Bab bulbs? (they are double filamented) Bad dimmer switch? Bad low-beam relay?
It is perfectly legal to drive with high beams on, as long as you dim them when required by local law.
If the high and low beam headlights stopped working on a 2000 Toyota Tundra, the fault could be with the headlight relay switch. This is a large fuse located in the fuse box on top of the battery.
Change the globe or lamp. H4 type globes contain the high and low beam, so whilst low beam is working OK the high beam part is likely blown.
spot beams are usually for local channels beamed into a certain area. they have nothing to do with tuning the satellite dish.
what state are you in
OK, the REAL reason this happened is that the GROUND from the LOW BEAMS opened and did not return to the dash. This causes the HIGH BEAM indicator to not work (because believe it or not, they use the low beam filaments as a return for the low beam indicator!), but the high beams to still work OK. Rather than disassemble the whole dash & turn signal assy., I just ran an additional ground wire to the LOW beams (through a switch, so I could disable it if necessary) and it solved the problem. I still don't have the little blue high beam indicator, but you casn tell if they're on or off . . . P.A.