light problems

I have a 2000 cavalier and im having problems with the passenger side head light it dimer then the other and causes the service light to come when you shift it into gear when the driving light come on if anybody has the answer to fix it that would be great:banghead:

bulb could be getting weak or wire probably corroded, you will have to follow wiring back from headlight itself . pay close attention to the connections. while you are doing that might as well check drivers side as well