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Miata Headlight swtich??
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Author:  Mnot [ August 3, 2019, 8:47 am ]
Post subject:  Miata Headlight swtich??

I am using a 1990 Miata steering column and will be using the turn and headlight stalk. I figured out the turn signals (3 striped green wires) but cannot figure out the headlight switch. I believe it uses 4 wires, 3 are red with stripes, and the other is white with a black stripe. 2 of the red wires have continuity unless high beams are selected via pushing the stalk back or pulling for "flash to pass". I am completely lost on this and any help is much appreciated!

Author:  jaf [ August 3, 2019, 12:36 pm ]
Post subject:  Re: Miata Headlight swtich??

The wiring document will be your new best friend. https://s3.amazonaws.com/miata/miata/1990+Wiring+Diagrams.pdf
Learn how to read it and make sure you mark up any changes (radio, air bag, HVAC delete) you make. I have pictures of my marked up copies in case I loose the originals.....yes they are that important.


I used the left hand stalk and it keeps all of the stock Miata functionality (headlights, turn signals). I removed the right hand windshield wiper stalk. I actually kept the hazard/headlight-pop up switch. The hazards switch I left unchanged, but the headlight pop-up switch now runs my windshield wiper motor. Since I used LED taillights are had to do a mod to the blinker switch. Link here: https://forum.miata.net/vb/showthread.php?t=335534

Author:  Miatav8,MstrASE,A&P,F [ August 3, 2019, 3:46 pm ]
Post subject:  Re: Miata Headlight swtich??

Get out the magnifying glass to see the numbering of the positions on the back of the switch or just draw a picture of the pin arrangement and number it as you see fit.

Make a truth table with the pin numbering across one side.
Add each switch position across an adjacent side (i.e. off/park/head with hi/head with lo/flash to pass).
Draw a grid.
Set a multimeter to the ohms continuity tone/beep function so the leads cause it to beep when touched together.
Fill in the blanks one at a time.

Once you know what the switch does, you can design a circuit around it.
To prevent melting the switch, use relays to the headlights for hi and lo beam.

Author:  Mnot [ August 4, 2019, 8:19 am ]
Post subject:  Re: Miata Headlight swtich??

Thank you. I now have the low beam and the high beam sorted but not sure how the high beams turn the low beams off when selected. I will keep at it.

Author:  Miatav8,MstrASE,A&P,F [ August 4, 2019, 9:40 am ]
Post subject:  Re: Miata Headlight swtich??

There should be a terminal that has continuity to another terminal that is common to hi and lo.
This is the source (12 vdc, B+, batt positive, etc) through a fuse from the battery to power both the hi and lo headlights.
The source will make a contact in lo that is not made in hi and a contact in hi not made in lo.

These contacts should go to the control side of a relay for hi and a relay for lo, with the other terminal of the control winding to ground.

Author:  rx7locost [ August 4, 2019, 11:50 am ]
Post subject:  Re: Miata Headlight swtich??

I thought this looked familiar. We covered this last year didn't we?

viewtopic.php?f=44&t=19566&hilit=miata+headlight&start=15

Author:  Miatav8,MstrASE,A&P,F [ August 6, 2019, 5:55 pm ]
Post subject:  Re: Miata Headlight swtich??

I guess so. We cover a lot of things. :cheers:

I'm not sure where I got the schematic.

Author:  Mnot [ August 7, 2019, 8:08 am ]
Post subject:  Re: Miata Headlight swtich??

Sorry guys :cry: I have been referring to a printout for the Hazards all and they work great. But, I forgot that that thread included headlights and that you both went into great effort and detail.

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