I have a 1998 cavalier. Recently the left headlight stopped working. I replaced it, and nothing happened. I then changed the socket thinking the socket itself might be fried and still nothing. I have also checked with a voltmeter to see if there is power going to the socket and found that one side had 12 volts registering and the other side of the socket had less than 2 volts. It sounds like it is getting shorted out. Can this just happen out of the blue and what can I do to fix this problem. Thank you for your time.

I would like to know if it is just the low beam, high beam or both that you are having trouble with.

This will help us determine the course of action.

Assuming that it is both, it sounds like a loss of ground (-12 volts). On cars, the ground is the chassie. Any point between the 12 volt positive battery terminal and the chassis will read 12 volts.

In the old days, this ground to any 12 volt device was done right at the chassis where the light was instlled. Only needed 1 wire for the light to work. Negitive 12 volts was pick up through the mounting screw.

With all the plastic used in modern cars, they have to run a wire from the light scoket to the chassis at some point. That may be where your problem is. This applies to any light on you car.

If you know which wire is going to the light is ground, then check the resistance between it and the chassis ground using a ohm meter. This reading should be 0 to no more the 2 ohms. Anything over that, you have a dirty or no contact to ground.

You can also check the voltage between chassis ground and:
1) the low beam wire when low beams are on and
2) the high beam wire when high beams are on.

Again, if you get 12 volts, then it could be that ground.

If you hve a newer car that have driving light that come on when the engine is running, there may be other possible problems.

This message has been edited. Last edited by: Walks On Water,

It is only the low beam that is not working.

the ground would afect both lights . it sounds as if the power for low beam is bad, witch would say there is a broken wire or a loose conection between the head light low beam wire and the switch lowbeam side only. check the switch for loose wire conector.
also check and see if you have 12 volts from the switch lowbeam side only.
possable bad switch , but it sounds like a loose conector.
for a test you can run a hot wire from the batery to the low beam side of the light and it should light up. that will tell you if the ground is bad.