2000 Pontiac Bonneville high beams work but not head lights

SOURCE: change head light

You should be able to reach under the hood into the headlight assembly and grab the bulbs and twist them off if not then you have to take off your entire headlight assembly then take the bulbs out.

SOURCE: low beams stopped working high beams work fine

Either both bulbs are bad(I've seen it before) or your
dimmer/headlight switch is bad. If you can without pulling the bulb, pull plug from the light. If it's a 4 lamp system pull the low beam. Do this on the left side as the right feeds from the left. With a 12v test light, check for power. (with lo beam on) if you have
power, change the lamp, if you don't it's most likly
the dimmer switch at the steering collum.
Hope this helps Good luck

SOURCE: driver side head light does not work...the high

Change the bulb. High and low beams are separate bulbs located in the headlight housing. Im not sure on the 07 but the earlier design Yukon (02)you have to pull out a pin located under the hood on the top of the light housing in order to remove it.

SOURCE: low beam head lights turn off while driving now

hihi...
there may be loose connections with the bulb socket. so they turn off and on while driving.

now the loose connection might hav developed and the wire might have came out from the socket so the light dosnt glow now.

try checking and putting back the wire in place

SOURCE: 2002 gmc safari head light

First check, is there more than one headlight bulb, if so, the low beam bulb has failed, needs replacing.

If not you'll probably find that the head light bulb has a double filament, low and high beam. The low beam filament has failed. You have to replace the bulb.