Hid issues

I just got some used hids retrofitted into hella 4000's and they worked great for about a week then sometime in between one of the lights won't work... I don't think it's wiring issues since the other work fine, and I don't think it's an aux switch issue since only one is out not the set... Maybe a bad ballast or bulb? Any way to test either to see which is bad? Kinda sucks I just got these and now one doesn't work but on a lighter side my large outlaw raptor goodies should be on the way next week! Method nv's here I come!

swap a working bulb from one light to the other or take a ballast from working side and connect to the non working side. that will help u determine bulb or ballast

also if your wire harness grounds on both sides re connect the ground on bare metal.

Good idea guys thanks! The wiring was done up by previous owner to aux switches 1 and 2 so ill trouble shoot after I get my truck back tomorrow... Wish me luck getting my heated seat issue fixed, bad heating coil and sensor being replaced