Hello, I am totally stumped with this, I have a 1990 Honda Civic with a 1989 Acura Integra Engine in it (Engine Swap), and it won't start.

Nothing works, the lights, the radio, hazards, defogger absolutely nothing.

Of course your thinking the battery is dead but I checked the battery and it is fine. I had the car up on jacks and the car started and it would run perfectly, then 5 min later I lower the car and it doesn't start or anything! Also the hazard and defogger button creat a buzzing noise coming from a little black box near the fuzes.

PLEASE HELP ME

Take a multimeter and test all under-hood and under-dash fuses.

O yeah sorry to add I already did that to and I checked every fuse

Are you sure you don't have an anti-theft device that's kicking in?

Nope I don't have any it's a 1990 civic so there's no stock one or anything

Does it crank at all?

Nope and I know for sure the start works, I just replaced it and it worked 5 min prior to trying to start the car

My hypothesis is that your ignition switch is bad, because of catastrophic loss of the starting system, warning lights, dash lights, etc. This is just an educated guess. So wiggle the ignition switch key and play around with it and see if anything happens. If that doesn't work, take the switch apart and examine it. If this makes sense to you, then look at this link first:

http://techauto.te.funpic.org/ignitionswitch.php

If that didn't solve the problem, then follow the steps below:

Are battery terminals clean and tight? Have you checked main engine grounds? Have you checked the fusible link? Take your multimeter and start checking voltages from the battery to the main relay. One main flow is from the battery to the under-hood fuse/relay box; to the ignition switch; to the under-dash fuse/relay box [ACG (S) fuse, No. 24, with SRS, or No. 12, without SRS]; to the main relay, gauges, alternator, and ECM. Double check that the ACG (S) fuse, in the under-dash fuse/relay box is good. This is an extremely important fuse. Make sure alternator is good, particularly the voltage regulator.

Another major flow is from the battery to the under-hood fuse/relay box, to the ignition switch, to the clutch (A/T) interlock switch, to the starter solenoid. Check battery voltage at the starter solenoid. Make sure the clutch (A/T) interlock switch is good. Basically, if the engine won't crank, check the battery, alternator, fuses, or starter solenoid for power.

All right I will do that tomorrow thanks man

Because of the general electrical system failure, I would check power at each fuse using a multimeter. Turn ignition ON, set DMM to DCV, and touch the leads to the test points on each fuse. Note the voltage reading at each fuse, in an attempt to isolate where the problem is.