Maybe you should consult a car audio shop or the manufacturer.
The capacitor is about 10" s long and 4" s around and has a LCD display on the top of it. It says 1 fareded on it I believe. When it's hooked up it has little lights in it that are blus and flash on and off every now and then. And I don't know if it's supose to do this or not but every now and then it makes a whistleing sound for a few seconds. Any info or help in this matter would be greatly appriciated.
It should read zero and be off - there is no 12V source in most garbage bins.
Otherwise the display should read whatever dc voltage is present.
Ideally that is up to 14.4V for most systems when charging and down to battery voltage when not (ie, 12.7V and lower).
Do not buy a replacement cap if this one is faulty - unless you know why you require one, as opposed to those that think they require one and get conned by the ignorant and rich.