Take that cap out first to see if that is the problem..It may be a bad cap..Caps are pretty much useless and do not perform up to the specs,and are pretty much a gimmick to buy.Look cool ,but are basically CRAP!, If taking that out works, then that was your issue..If you want some juice at the amps, I recommend putting a small battery/or a battery in its place, but at the wattage you are at..I dont see why you are having dimming issues, unless your stock alternator or batt under the hood is bad.Can go to Orielys and get it tested with ,and without a load on it for free??Yet,take that cap out first try that..Id still get your batt checked out though..Its free???