Could be the ballast.
Make sure all the wires are plugged in, and secure.
The ballast could be not getting all the power it needs to turn on.

---------- Post added at 09:54 PM ---------- Previous post was at 09:54 PM ----------

Take off your passenger ballast and try it on the drivers side, and vice versa and see if it works.

 

Okay, I'll give it a try! Just a question, if a ballast is wet does it not always function properly, seems like I get the issues after downpours.

 

Where are you grounding? If you're not using the ground below the headlight bracket, try moving it there and see if that helps.

 

Did it work?
I've never had a problem with my HIDS in the rain..

 

Just changed my ballasts, the one from the driverside works perfectly fine on the passenger. My driverside ballast isn't getting power, it isn't warm like the other one.

Also, opened up the main compartment of my relay harness and one of pink wires is partially discoloured where it connects into the pins. I'm assuming this is what's causing my issues.

Should I just order a new relay harness and try that?

And Jackson, I've removed all paint where my grounds are. I have both sides grounded to either fender bolts.

 

You could order a new relay harness.
Id try that, and if it doesn't work, it could be something else electrical.
When you turn on your lights, do you hear a loud click?

 

Turns out my warning canceller was fried. Unplugged it, gave my ballast power again! All good now guys!

But, while I was doing this, I dropped a pin that holds the front grill flush to the engine compartment down into my front bumper.

Is there any possible way I can get underneath my front bumper without removing it? It's making an awful flicking noise when I drive now.