Technical Cinq Sporting Tachometer Wiring

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Technical Cinq Sporting Tachometer Wiring

MathiasDKling

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Hello all!

Does any of you gurus care to tell me how the tachometer is wired, on a Cinq Sporting?
As parts of swapping the ECU, throttle body, ignition unit etc. From a Cinq Sporting, into my 91 Uno, i need to decide on how i want to run the tachometer from now on.
The Uno Tachometer runs off the no. 1 pin on the coil. Pretty standard for an electronic tachometer i suppose. That would mean it gets 2 signals per crank rotation, with the current distributor ignition.
The new ignition system, should i take the coil charging signal off a single coil, would by my thinking only give a single pulse per crank rotation. Therefore the tachometer would only read half engine speed.
I figure i might be able to make something up, with some one-way diodes, and joining signals from both coils, at the tachometer. But i wondered how the original tachometer in the Cinq Sporting had been wired. In case the tachometer runs on the same principle as the one i have in the Uno, then it must be getting a 2 pulse per crank signal, from somewhere else.

Infuriatingly i do own a Cinq haynes manual, but it doesn't include the tachometer, so that's no help.

I hope that someone here might be able to help me out, be that by a wiring diagram, or a simple explanation.

Best regards from Denmark
Mathias
 
Hello,

FIAT's eLearn, at least the part of the scanned paper docs that is available online, does not cover the Cinquecento Sporting version :(

Check the downloads section of the forum, some time ago I've uploaded the Seicento docs there, so perhaps that could be useful :)
Hello!

I went to look in the downloads section, and found an Italian workshop manual containing what i needed. The Sporting tachometer gets it's signal from the negative activation signal to the fuel pump relay. Fuel pump must be getting a PWM signal, to limit the amount of fuel recirculation I'm guessing, but will measure this on my other Cinq Sporting, to make sure. Otherwise i don't see why the Tachometer would be able to use the activation signal, for an engine speed signal.
Thanks for your help. Im still learning to navigate the Forum!
Best regards
Mathias
 
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