It sounds like you have several problems and are lumping them together in one neat little package.
the code p0480 refers to the cooling fan
here is a link that may help you with that.
http://www.obd-codes.com/p0480
as far as the head lights flickering start with basics
Do you have a good battery and good connections with no corrosion at the terminal ends.
Is the alternator charging?
Which switch did you replace? and why?
The headlights should be easy to figure out what is going on, measure the voltage to the headlights and check the grounds to the head lights as well.
the DRL , what is this? are we supposed to understand your short hand?
If you want help take the time to spell out each word.
What you have wrote makes me believe that you should bring your car in to a shop for diagnostics and repairs.
to fix these issues you will need a factory service manual a DVOM a Computer safe test light and basic hand tools.
Once you have the needed tools and manual let us know and I will continue to help you.
If not wait for other that may pitch in with vehicle specific data that may be of use to you.
