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-   -   MS installed, No more dashboard tach (https://www.miataturbo.net/megasquirt-18/ms-installed-no-more-dashboard-tach-44954/)

94mx5red 03-16-2010 08:44 PM

I tried it on the cheap, and stuck the ends of the resistor in the diagnostic box. The tach needle did move about a millimeter when the key went to 'ON' position, then nothing when running.

I am about 95% sure that the ends of the resistor were touching the contact points in the d-box. Should I go ahead and try to do it properly, or does this suggest something else?

minileprechaun 03-18-2010 02:29 PM

so this may be a really dumb question... but i plan on finally getting around to installing the MS braineack built for me a while ago .. and i don't know how to tell if i have a 1995 or 1995.5..... where or how do i check for 3 or 4 wires in the coil connectors .. rather .. where are the coil connectors?

Braineack 03-18-2010 02:32 PM

The coilpack is what your plug wires fit onto. there should be two connectors coming off the back of it and plugged in somewhere behind the fuel rail. See if there are 3 or 4 wire going into each connector.

To prevent this in the future I'm simply building the tach circuit on each MS I build, since the circuit itself requires the pull-up, there will be no need for adding the resistor and if you have a 95.5-97, you can turn on the tach output in software.

hellothere 03-19-2010 01:46 PM

I finally got this thing working. The wire for the dash tach on my car is at 1f! Apparently in 95.5 Mazda decided to fuck with everyone!

ArtieParty 05-13-2010 10:53 PM

This kid Slacker also has a 1995.5 and couldn't figure out why his tach wasn't working. I thought I remembered something about this topic and did a search. Why isn't this a sticky in MS?

longuyen88 05-15-2010 09:57 AM

I have a 94 DIYPNP. My tach drops out at WOT. I will try the resistor in the diagnostic box. Anyone have a picture of how they installed the resistor in a clean manner?

heychris 08-17-2010 01:59 PM

Does a MSII on a 97 need this tach output circuit in a standalone configuration? I understand 4l is the Tach lead on the stock harness.

Joe Perez 08-17-2010 02:02 PM


Originally Posted by heychris (Post 617648)
Does a MSII on a 97 need this tach output circuit in a standalone configuration? I understand 4l is the Tach lead on the stock harness.

Yes, any MS on a '97 will require a tach output driver. And yes, on a '97, the tach output is a black/white wire on pin 4L.

heychris 08-17-2010 02:07 PM

Thanks..

In this configuration does it need a resistor on the diagnostics box?

It says try resistors between 1k and 10k. What do you use?

buffon01 08-17-2010 02:16 PM

As far as I know if you have the tach circuit you DONT need the resistor in the DB.

Braineack 08-17-2010 02:27 PM

which is because part of the circuit built within the MS is a 1K pullup to 12v...

which is exactly the same as the 1K reistors on IG-(tach signal) to B+(12v)

webby459 08-17-2010 02:32 PM

Lol, when I switched to COPs I got the resistor but never put it in. Since then I've had three co-drivers autocrossing with me. The little funnies always ask how they will know when to shift. As if they can't hear the limiter.

buffon01 08-17-2010 02:40 PM


Originally Posted by Braineack (Post 617671)
which is because part of the circuit built within the MS is a 1K pullup to 12v...

which is exactly the same as the 1K reistors on IG-(tach signal) to B+(12v)

Well yeah, all I was trying to say is that depending on the car is either one or the other. W.e ya kno wa Im sayin


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