Odd headlight issue with 03 4.6is
 

I searched headlight issue, flicker etc and went through the first few pages that closely matched but haven't found anyone who had this particular issue.

When I turn on the headlights on my wife's 03 4.6is, the left and right HID cut on and off really fast for about 5-10 seconds opposite one another before the right finally cuts on and the left stays off. Very few times, both lights will be on but the left will be a different color. I tried swapping in new bulbs but that didn't change anything. I haven't tried the ballasts because I find it hard to believe that both ballasts would be affected by this but it's not impossible I imagine. The only other thing I could think of would be a bad light control module or perhaps a faulty ground but everything looked fine when I pulled the light.

I would hope to get some personal experience/suggestions before buying replacement parts.

take a good look at the wires. my wife's e46 headlight would cut in and out when I would rotate the steering wheel. after further exam, one of the wires was barely hanging on.

give it a nice tug and make sure all the wires are secure.

any codes popping up?

I have not experienced this on the x5 but on another car and it turned out to be a tied to either an igniter or ballasts on their way out. Not sure that will translate to x5 though.

I have also a random gremlin which occurred a few times, similar, it throws a check lowbeam error - my only thought is maybe the ballasts are slowly going and taxing the LCM which is freaking it out

Usually with a flicker-flicker-dead symptom it is indeed the ballast. Same happened to me once a swap cured it.

A color change in the bulb depends on how long it stays on. Naturally the Xenon bulb needs to "warm up" for a few seconds to reach operating / color temp.

But the situation you described is a bit difficult, in a situation where they DO stay on, maybe not enough voltage? A bad ground would likely make them default off, or so i think. But the ground inside the light is rather sturdy, now wiring from the light to the LCM is another story and even then they are independently ran, so the LCM just may be the final factor.