When I turn on my headlights only one light turns on but when I turn on my brights the other three come on and the one that was on previously goes off. Any ideas whats causing this? If you don't get what I mean, please refer to me wonderful illustration below ...


X - Light that is on.

Normal Headlights
[ ][ ]______[ ][X]

Brights On
[X][X]______[X][ ]

 

Headlight switch sounds like the culprit....

 

try switching the 2 out lights and see what happens. if the problem reverses then you have 2 partially burned out lights. if not then yes its a switch issue. the low beams may also have a 2nd filiment for hi beams. this happened to me many years ago.

 

Replace the two outer headlights. There are two filaments in them and more than likely one in each is burned out.

 

Quick update: When I have my brights on now all four of them kick on. It has been like this for a few days so far, but with the brights turned off it still is just the one headlight that turns on.

@ MadMike: Can I just replace the bulb or do I have to get a whole new headlight?

 

Unless it has been changed for a different headlight system you need to replace the whole square light. Its a sealed beam. You may want yo wiggle the connections. Maybe even put some dielectric grease on them. I have also seen where the pin on the back of the light would break loose.