My 1993 mazda miata keeps blowing the btn fuse as soon as you put one in the fusebox. only the headlights,a/c and blower work. all other lights are not working. if you disconnect the battery and put a new 40amp fuse in then reconnect the battery the hazard lights work for a minute then the fuse blows again. are the diodes in the alternator bad and causing this? all other fuses are good

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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hot wire touching metal fuse blows so you don't burn up the wiring get it tested and fixed soon could be dangerous to keep putting in a new fuse

Hi Lee and Chuck, Seems you have a serious short circuit in your vehicle. The fact that when the vehicle stands it will need to be jump started would seem to confirm the same. The power seems to be draining somewhere! The fuses which blow will give an indication of which circuit is shorting. If your brother wired in a music system or radio, disconnect it and then see if the fuses still blow? If they stay fine you know where to start. The music system is connected to the lights for night illumination of the controls. It may be that the earth connection has been mixed up with a power cable? If the vehicle runs fine during the day and does not give problems when restarting, it would be doubtful that there is damage to the alternator. You can check it fairly easily by connecting a test meter to each of the terminals. Start the vehicle and if while cranking the voltage drops below 8 volts, get the battery replaced. If it remains at about ten during starting that's fine. Measure the battery voltage before starting and confirm 12 volts. Once started the voltage should be at about 13 volts if the alternator is charging and when the horn is pressed and the wipers turned on together with the heated window, the voltage should climb to about 13 and a half volts. If the voltage remains unchanged or drops the alternator is damaged. Usually the head lights would be turned on to carry out this simple test but as the fuses blow you can do that when you've found the short circuit. Good luck and best regards John

Weird ! If each one has it's own fuse I would take out one fuse, flip the light switch so only one of them moves, then put the fuse back in and they should then be in sync. Check it out.
Might actually work. I have a Miata but I never had that happen.

Good Luck

Sounds like both dim filaments are broken.
But before you go off and buy a new headlight, try removing the headlight and run a positive lead to each side of the hi and low connectors. Negative is the center pin, like this -_- if dim works with a battery, then you need to replace your dimmer switch. If not, its the headlight itself.

BTN stands for Body/Tail/iNterior. It protects the HAZARD, ANTENNA, ROOM, STOP, ILLUM and ABS fuses in the cabin fuse box, which in turn protect the hazard lights, antenna, ECU memory, brake lights, tail lights, ABS, power locks, clock, horn, illumination, stereo, HVAC, interior lights and alarm. __________________

Sounds like too much draw on system. To test turn off radio. I would route separate heavy wires to power radio. Use a 12 volt relay to control (e.g. 30 amp auto relay). Connect normal radio power to power relay (so that key controls radio)

costs like $100 an hour for automotive electrician. use a curcit breaker (looks like a fuse) its silver put it in wher the blown fuse is. buy a compass. and runn the compass over the wiring . when the compas moves in the direction of wiring its in that area. a short curcit creats a magnetic feild.

I have a problem with my tail lights in my mazda. Brake lights working great but the light that supposed to be working during night time are not. By the way the front lights are working too! Also the light of the panel inside is not working. Can anyone please tell me how to fix it?
Thanks alot in advance!