Ok! So I am changing out my halogen lights on the exterior and I have my everything in except my headlights and my break lights.

Now for the questions
I changed out the turn signal flasher relay, and after I closed everything up, I thought "Wheres the hazard flasher relay?" I cant find anything about it for the 90 and up.

SECOND
When my headlights are on, my turn signal Indicator lights are always running, when they didn't before the LEDs. What can I do to fix that.

Third!
Are the front and side blinkers supposed to alternate? I've found people explaining the principle about it, but they don't say if the are supposed to or not.

Finally
when I decide on what I want to put in for my headlights, how do i fix the fog lights not turning on with the headlights on. I want them to work like they are supposed too, on with dims, off with brights.

 

"Brake" lights First, no idea (can find out with a 1996 service manual if that helps). It might be the same one though Second, led lights in c4s will do that if they are reversed in the socket. Or they just do it and you need a resistor to add load so the car doesn't think the lights are out Third, what are you talking about? This needs way more info to make sense

Finally, also more info needed. As in, what's the problem?

 

I installed LED headlights and taillights. Front turn signal lights. Rear center brake light. Interior lights. Hood light. I'll get to the side markers later. Some people add the resistors. I think they are too cumbersome and also I'd like to not cut wires so I can go back to stock. For the turn signal, I used and electronic flasher. And, at least my car, the flasher was on the passenger side behind the breadbox.

CEC Industries EF32 Electronic...
I didn't have a problem with the headlights. The taillights, my hands and arms are still recovering from the scratches.

 

I was able to sort out everything!
When i put in the LED Electronic flasher, my side blinkers were alternating from the fronts like normal, i just didnt know if they were supposed too or not. Now for the indicator lights on the cluster for the blinkers being on with the headlights. I ended up putting in resistors on both sides of my blinkers. The LEDs don't pull enough power and so the car thinks the lights are out.
I just tied in the resistors into the blue wires for the blinker and grounded it. I can disconnect everything and make it go back to stock if I wanted to put the incandescent lights back in.
I haven't put in LED headlights yet, I had just received and put in my new HELLA hlmp kit, which are amazing! I did a test drive when it got dark, although it was very very misty out, but I was still able to see. I may or may not switch them to LEDs but if I do I'll get some plug and play H4 resistors, that way the fog lamps still work as factory.

I never had a power draw problem so ill put in resistors, I like the LEDs they are brighter, and makes me more visible to other drivers.

 

This is for the 1984 but from what you are saying it is probably very similar on the 1990.

With "MAIN LIGHT SWITCH" off ( Brown wire ) the "LEFT TURN INDACATOR", "LEFT FRONT MARKER" and "LEFT TURN LAMP" will flash in sync ( blue wire from relay ).

The "LEFT FRONT MARKER" will ground thru all lamps in the parking light group, including rear lights. On this picture you have the "LEFT FRONT PARK LAMP" as example on the brown wire.
With parking light on you have 12V on the brown wire and now "LEFT FRONT MARKER" seek ground on the blue wire thru "LEFT FRONT TURN LAMP" and "LEFT TURN INDICATOR" in the dash.
Whith turn signal on the "LEFT FRONT MARKER" will get 12V on both sides and this is the reson it is alternating with the front turning light.

By replacing the front "LEFT FRONT TURN LAMP" with LED a lot more current will go thru the dash indicator. A resistor to ground on the blue wire will fix this as you described.
You might also need a resistor on the brown wire to ground if the side indicators does not flash with parking lights off.

When the desigher of the electical system use other more powerful lamps as ground path in some functions you will get strange effects when converting to LED.