I've checked fuses, replaced both the headlight module and the switch's. My blinkers, hazards and reverse lights work but, no headlights or running lights/ dash lights when I turn the switch on. Can anyone point me in the right direction?
I have a multimeter ready to start checking but I'm not sure where to start. I don't have any experience with electrical problems.

 

Did you check the grounds on the front core support and the wiring to the headlights for broken wires?

 

I'll do that first thing tomorrow morning and let you know.

 

Well I've checked the grounds and the fuse by the driver side headlight, all good I'm only getting 6 volts to the headlight motors and no power to headlights , I swapped all 3 relays and it made no change.

 

Only getting 6 volts there sounds like a possible high resistance connections. Make sure every connection is clean and tight. You could consider disconnecting the power feed to the light and running a temporary wire (recommend an inline fuse holder between) straight to the headlight motor from the battery. If it works fine, you know the problem is in your power feed. If not, you could do the same with the ground. Run in straight from the battery. If things work, your ground is the problem.

 

Well I think my problem is definitely wiring somewhere, they put a corvette engine in with a pro charger so it has a lot of wires everywhere and I know nothing about them. I really don't want to have to pay a shop to figure this out that's for sure.

 

Of course "they" did. EVERY engine "they" "put in" is "out of a Vette". Not to be mean or anything, but I'd guess that the odds your motor is ACTUALLY "from a Vette" are relatively small. Note that I am NOT saying that "they" lied, or even that you misunderstood "them", or anything of the kind; just, ODDS ARE, any motor that "they" are LIKELY to have come up with, didn't come "from a Vette". The operative concept here being, LIKELY. "Vette engine" (or any other part) is the single most common untruth that exists about Chevy motors, and to those of use who've been around the block a few times more than most, is an INSTANT RED FLAG for an exaggeration, if not an outright lie. Basically, if you didn't SEE IT WITH YOUR OWN EYES, or you haven't checked part #s or certain unique features, it didn't happen. Wouldn't surprise me if it has 193 heads for example, if it's even really a 350 to begin with.

That aside, what else doesn't work? Anything? I don't know offhand what else is on the same fusible link as the headlight switch in a 90 Firebird, but I'm sure there's plenty of stuff... could be the radio, the HVAC, the power windows / locks / seats, rear widow defogger, etc. etc. Do a thorough survey of what does and doesn't work, might help you pinpoint what they all have in common.

Or, just check the fusible links, which are at the starter, and connect THE ENTIRE CAR to the battery. There are 2, or maybe 3, and each one feeds a sizeable fraction of the electrical load in the car. Needless to say lots of things share each one of them. If one is bad, it can cause all the things that are supposed to get power from it, to not have power. Including 12V not reaching the HL sw and therefore every light connected with it not working.

 

Radio works, power windows work, power mirror doesn't , the rear hatch release and defrost doesn't , door lights, dash lights and headlights don't work , windshield wipers, turn signals and reverse lights do work. they removed the windshield washer fluid container completely.

 

Mang...

No telling what sodomy has been perpetrated on that poor car. At a certain level there's not much anybody out here can tell you, besides what you will have to dig up on your own with some serious archaeology. Best we can do out here, where we can't see it, is just GUESS stuff. Not particularly productive. After all, you can see it, we can't.