Where is the starter fuse on 1990 miata - 1990 Mazda MX-5

Question edited for clarity.
Question moved to model category.

Yes, you are correct, disconnecting the fuse box has broken the pairing between the key and the immobilizer system. Did you remove the main connection plugs to the fuse box? My thought is that those connectors have never been removed since the car was built and breaking a remaking the connection, you might have some connections that as not as good as they should be. Pull the connectors again and give them a good spray with electrical contact cleaner (that is NOT WD40). Then reconnect.

There is various ideas on resetting the Immobilizer here.

https://www.google.com/search?q=mazda+miata+immobilizer+system+reset

Or a Mobile Auto Locksmith

https://www.google.com/search?q=mobile+auto+locksmith+near+me

Just for fun, here are the Fuse Box locations and diagrams. They have changed over the years, and as you didn't state the year, here is all of them.

Mazda MX-5 Miata (NA; 1989-1997) fuses

Fuse Box Diagrams https://fuse-box.info > mazda > mazda-mx-5-miata-na...

Here you will find fuse box diagrams of Mazda MX-5 Miata 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, get information about the location of the fuse ...

Mazda MX-5 Miata (ND; 2016-2023) fuses

Fuse Box Diagrams https://fuse-box.info > mazda > mazda-mx-5-miata-nd...

Fuse box diagram (location and assignment of electrical fuses) for Mazda MX-5 Miata (MX5) (ND; 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023).

1990 miata Don't waste your money on unnecessary sources and unwanted repairs. Get this manual online under $10-15 and get complete guide on whether to repair or not, service it, and how to repair etc

There are 2 fuse boxes. One under the hood on the passenger side and another under the dash on the drivers side.

I think they're both in the same box as the main 80A fuse. I replaced my main fuse a while ago and while doing it caused a brief short, spark flew. But I got lucky because after replacing it everything worked.
Get a Haynes service manual, it will help.

The fuse is the most likely problem. The fuse for the horn is the same as for the stop lights. 15 amp fuse located in the fuse box under the dash on the drivers side. If it's blown and it fails again once you replace it, the horn is bad.

You'll have to inspect the brake light switch at the pedal box assy. Damaged switch or wiring could give the previous symptoms you describe.! Good luck

There is a lever to open gas cap in your miata. It should be in the center console between the seats. This is true for my 1990, and since the 1990-1997 Miatas remained virtually unchanged, this should be where it is.

check that there is a good connection from the earth to body (a lot of electrical problems are earth related) also that the connections on the battery are firm. check that the battery has good voltage.

remove the key from the ignition get a 21 mm socket and wrench and try to turn the crankshaft clockwise to see if it moves if it moves try to push start the car push the car to about 1 to 2 miles an hour with the key in the on position all dash lights on eg. check engine, air bag, etc. put in second gear and drop the clutch if it starts it's likly you have a bad starter

> Any suggestions or reference to free wiring diagram downloads??

It doesn't seem likely since most of that kind of material is copyrighted works. I think they would take offense to putting it on the web.

You might get some help (or even emailed diagrams) from a fellow owner.

Check here:

http://forum.miata.net/

Good luck-