Tach signal with standalone MSI
#23
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Originally Posted by Braineack
I'm almost positive it's the same deal with the 1.6Ls and standalone. The b/w tach signal from the coils should have 1V provided to it, else the signal cant power the tach on the dash....
Originally Posted by j_man
Yes
the '94-'95 is the exact same thing as the '90-'93. The stock ECU does the pull-up.
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#27
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It definitely ain't the same as the 1.6s if that's the case. The 1.6 igniter has a black/white wire coming out of it that feeds back to the ECU, however the tach signal is a yellow/blue wire which goes from the igniter to the tachometer and the diagnostic connector. On my car (MS, full standalone) I left the yellow/blue wire alone (still goes from igniter to tachometer) however my black/white wire is completely disconnected.
#32
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The idea of a pullup resistor is that it weakly "pulls" the voltage of the wire it's connected to towards 5V (or whatever voltage represents a logic "high"). However, the resistor is intentionally weak (high-resistance) enough that, if something else strongly pulls the wire toward 0V, the wire will go to 0V. An example of something that would strongly pull a wire to 0V would be the transistor in an open-collector output.
#34
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Anyone happen to locate the pin on the 1995.5 tach wire on the boomslang?
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#35
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You already fixed your problem, but I just want to feel important. ![](https://www.miataturbo.net/images/smilies/smile.gif)
https://www.miataturbo.net/forum/showthread.php?t=9723
https://www.miataturbo.net/forum/showthread.php?t=10921
-Mike
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https://www.miataturbo.net/forum/showthread.php?t=9723
https://www.miataturbo.net/forum/showthread.php?t=10921
-Mike