Tach signal with standalone MSI
#23
Boost Pope
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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.
#27
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
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? Position 2I has no wire on my cars ECU harness. I'm guessing but haven't had ANY time to check it out, but I'm guessing that its position 1F because my documentation shows its not used but I think theres actually a wire there.
#35
You already fixed your problem, but I just want to feel important.
https://www.miataturbo.net/forum/showthread.php?t=9723
https://www.miataturbo.net/forum/showthread.php?t=10921
-Mike
https://www.miataturbo.net/forum/showthread.php?t=9723
https://www.miataturbo.net/forum/showthread.php?t=10921
-Mike