Headlights Don't Turn on (Out at the Same Time)
 

What I have checked already (All Good):
- Fuses for Low/High Beam (Check w/ Multimeter (Ohms) and Visually inspected)
- Relay for Headlights (Makes Clicking sound and Switch them with the fog lights)
- Battery Voltage
- Light Bulbs (HIDs) (They have a very small cloud inside but it's not big enough to indicate that it's blown. Auto Zone and NAPA agree)
- Alternate 105 Amp Fuse (Visually)

Previous Modification:
-I recently blacked out the inside of the headlight housing. I had zero issues after, as I checked all lights right after install and they all turned on.

Previous Problems:
- I had a moderate amount of corrosion on the Negative terminal of the battery and the terminal end.

With that being said, questions:
- Could a bad terminal be the reason why my headlights don't turn on? I cleaned 95% of the corrosion off with a wire wheel. Could some corrosion in that module that's part of the terminal end be the problem?

- Could it be a reverse polarity issue? I'm sure with how modern the BRZ is, there is reverse-polarity protection but I also know that it isn't always 100% effective. I have noticed NAV system gets no signal, at least when I'm in the garage haven't checked outside of that. Also, key-less entry has failed about 3 times in the last month.
EDIT: Key-less entry and NAV system are fine, I was just paranoid :)

Haven't Checked:

Ballast - I really doubt it would be a ballast because they went out at the same time, also didn't notice any damage inside.

Wiring Harness - I do not notice any damage to the wiring harness, I will probably have a mechanic test this at that point.
EDIT: It appears I am getting voltage to the headlight connectors, wiring up to that point is fine.

Headlight Switch - Really doubt this would be the problem, all the other features work fine.

I'm literally about to give in and get an electrical diagnostic. If I end up ordering the new Battery Terminal end w/ module, that may be my last straw. As I don't know how to deal or check with reverse polarity.

(FINAL EDIT) PROBLEM SOLVED: The problem was a loose connector from the headlight wiring into the Ballast.

Do you have a multimeter? You could see if there is any power at the headlight connector and start working backwards based on results.

I do. That's how I tested the battery voltage and the fuses. Are you talking about the Igniter/Ballast that connects directly behind the bulb? I have no clue how to test that piece.

So you have voltage at the headlight connectors?
If that is the case then yes your HID’s are shot. Most car manufactures build in reverse polarity protection. This probably saved the car. Cheep add on electronics usually do not.

This ^
It has been seen here before. Just be glad it didn't take the BCM out with them!

This is what I meant. Can you or have you measured the voltage at the connectors when the headlights are in the on position?

Is this the "connector" you guys are talking about?

https://www.subarupartsandaccessorie...1422286297.png

We are talking about the connector on the cars wire harness it will be 12v. The connector out of the power supply that connects to the HID lamp is high voltage don’t mess with that one.

Will wake you up in a hurry!

LOL

Bear with me guys. These connectors? Should I get an Ohm reading or Voltage? While the car is off yes?

You are looking for 12 volts from the harness. If it is there you at least have base power going to the ballasts.

Ok folks, I got a voltage read from the connectors driver/passenger side, measure in 20V to Ground, on the screws near the strut. These were tested on Accessory mode and I even turned the headlight switch on.

If I'm not mistaken, the wires to both headlights is the slightly thicker ones out of all the ones that go up to the connector right? If so,

Passenger Side (RED) wire reads: 12.35v
Driver Side (Light BLUE) wire reads: 12.30v
As far as I understand it, I will be buying bulbs and hopefully not ballasts!
EDIT: I will be inspecting the ballast tomorrow to see any signs of water damage or frying. If I do not see any signs, I will go through the "trial by error" method of buying a bulb.

Headlights are back on...

CULPRIT: Loose connection

The connection shown below was not tight, and the other was practically disconnected. Must have tugged it when re-assembling this.

Honestly not even mad, now I know how to diagnose this sort of stuff better and no extra money spent.

Thanks for your suggestions and tips guys.