Interior & Exterior lights flicker sometimes when car is parked or at light.?

I would reccomend that you get a better alternator. It sounds like the factory alternator is not putting out quite enough amps to power the aftermarket sound system and all of the original electronics in the car. If you do some research, you can usually find an alternator with higher output or a shop that can custom make one for your vehicle. You could also connect a capacitor to your new audio system and this will help to stabilize it by providing extra power for it to draw from. If these solutions do not work, then you more than likely have a bad/loose ground wire somewhere. Usually it will be either connecting to your battery or your alternator. Some times rust or corrosion will cause this condition so all you would need to do is clean the rust or corrosion and make sure the grounding screws/bolts are tight. Note: If you have a high power audio system in your car, make sure that the power and ground wires that connect to it are rated correctly for the amount of power that the amplifier is putting out. Then, make sure that the ground wire that connects from your alternator to the chasis of your car is at least the same guage wire as the ground wire on your amplifier. Or.... your current alternator could just be going bad.

Hey Guys, I have the same issue and trust me I have been everywhere. I went to a certified kia dealership dropped $1300 on repairs (new altenator, battery, improved ground wiring and replaced the drive belt) and still have nothing. Still having the same issue as before and no even worse. My left tail light is out, my right high beam sometimes works.. sometimes doesn't. and my horn is the same, sometimes work and sometimes it doesn't. please help me.