tacho signal

[Lmario]

What signal is supplied to the tacho on a '97 1200 ?

The signal comes from the cdi, but is it a dc voltage or current?
Or is it a pulse per rev?

please help.

mario

[Red01]

Just a guess, but I'd think it takes a pulse signal from the crank trigger.

[Lmario]

That's my problem, I had that same guess, but the signal(=pulse) from the ignition/cranck goes into the CDI and there is a different wire coming out of the CDI for the tacho. (acc. to Haynes)

So, it could be any type of signal...

[ray nielsen]

It might well be a TTL logic level signal, i.e. pulsing between 0 volts and +5 volts.

The ignition module is inductive discharge, not CDI (whch stands for Capacitive Discharge Ignition).  The internal ignition mapping takes place at TTL (for Transistor-Transistor Logic) levels of 0 and +5 volts and I'd guess the output to the tachometer does also.  

The Throttle Position Sensor on 2G models uses the same levels (+5 volts applied to the TPS, along with a ground) and receives an analog signal back from the TPS that varies from about 0.5 volts to 4.5 volts depending on throttle position.  

Transistor-Transistor Logic (TTL) refers to the internal configuration of the circuitry in the module and is very commonly used on cars and motorcycles these days.  Since most vehicles operate on 12 volts, it's easy to reduce it to +5 volts for the computer circuitry.

[Lmario]

I found it is indeed a pulse.
Now I need to find out how many pulses there are per revolution.

I understand most 4 cylinder engines give 2 pulses per rev.
Anybody know if this also applies to the Bandit?