Where is the yail light relay on a 2003 Mazda Miata located?

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).

This is a useful wiring diagram. I would say try swapping the relays over first and see if Low Beams now work and High Beams don't.

Other possibilities are two failed bulbs, or a broken connector. A good test meter should be able to trace this.

https://boostedmedia.net/automotive/videos/tech-videos/mx5-miata-headlight-wiring/


It does appear to be a known issue

https://www.google.com/search?q=2013+mazda+miata+no+low+beam+headlight

This suggests the combination switch

https://forum.miata.net/vb/showthread.php?t=531436

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Maybe you can find it with the wiring diagram.
http://www.mellens.net/mazda/mazda_miata_extra_manual/1996_wiring.pdf

i had a vehicle that did that before. Try the dimming switch if it has one

Should be located on the fender well under your hood in a black box, The top pops off and the location of your Fuel relay should be marked on the box cover. Good luck to you.

Something is wrong, keep after it. Look at the vapor recovery system...

Have it checked out by a professional body shop. If they determine the problem is related to a covered accident, then they can typically get it approved by an insurance adjuster.

try this link....you can also use a test light instead of an ammeter to see which circuit is draining the battery:
http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

Main Switch Is Located LEFT of Steering Wheel Down Low and there are 3 Switches and Cruise switch is the One on FAR LEFT

Same as the VIN otherwise it is on a plate riveted to the passenger side of the oil pan.

If are you talking about the Engine Model number it is a BP-14