Tach Signal, positive or negative?
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booya
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Tach Signal, positive or negative?
Is the tach signal coming from the trailing coil positive voltage or ground signal, anyone know? I looked in the FSM and it doesnt show voltage or ohms like the other gauges.
TIA.
TIA.
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rotorhead
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article on the ignition signals: http://www.teamfc3s.org/info/articles/demystifying.html . I would disregard the bottom section about finding TDC.
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booya
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Ive seen people run an aftermarket tach off the check connector right there (Y/L), so I take it its a standard signal used for RPM and not something RX7 specific? Pardon my ignorance please
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booya
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article on the ignition signals: http://www.teamfc3s.org/info/articles/demystifying.html . I would disregard the bottom section about finding TDC.
WOW, good read, thanks a ton for the link.
Now I know a few things:
- The RX7 tach reads similar to a 4 cylinder tach due to an ignition event occurring every 180* of the eccentric shaft.
- The Select signal is a 0-5v signal coming from the ECU that triggers the trailing plugs based on 0 and 5 volts.
So, two questions:
1) Does the tach signal itself vary between 0-5v or 0-12v?
2) Is the tach signal switched on negative or positive voltage?
If anyone can answer these I would be eternally grateful...
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HAILERS
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Buy a Fluke 88. Put it on dc volts. Idle the engine. Put the neg lead on a known gnd. Put the positive lead on the yellow/blue wire at the trail assy. Press the HZ (Freq) button on the meter. You now see the rpm diplayed.
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booya
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Im really not worried about displaying RPM on a multimeter, Im trying to run a non-standard tach signal through the OEM tach and the signals are not compatible. I figured the first step would be to figure out the OEM signal, then match it with a MSD DIS adapter or something.
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