I have a 4 wheel drive, 98 Rodeo.

One of the headlights works on full beam but doesn't on regular. It looks like its the same bulb for both functions. I had thought that I would just need to replace the bulb but if it works on full beam that suggests the bulb isn't broken. Could it be electrical or should I just go ahead and change the bulb anyway?

Thanks in advance for any light you can throw on this....

 

i think you have a short somewhere. check all your connections and fuses to help limit the possibilities of the problem.