Hi Josh, i had a look at the multi function pdf and it mentions a transmission speed sensor, which is 1 wire ;
Multi-Function Hub -
Most modern fuel injected bikes use a transmission speed
sensor. The Hub can be tapped into this sensor to display
vehicle speed and also to be used as a gear position
display for bikes that do not have a rotary type sensor
1 Locate the signal wire of the speed sensor (refer to the
service manual, NOTE section of this guide, or
Power Commander Line | Dynojet).
2 Crimp the supplied wire tap to this wire.
3 Connect the BROWN wire from the HUB harness to the
wire tap.
pdf link here;
https://www.mpsracing.com/instructions/DynoJet/MultiFunctionInstall.pdf
Our sensor is a different one like this;
The problem as popgun described very well is that it is what is known as a differential sensor, meaning it electrically floats with respect to chassis ground and the sensor circuit is designed to look at the DIFFERENCE between the two wires, the reason for this is the position of the sensor, you can mount it anywhere on the bike without having to worry about grounding the front fork hub or similar part to ensure a good return signal ( ground ) even after years of use.
However if you wanted to use the signal for another purpose you would have to look at both wires and specifically the difference in signal between the two
( See peter baron's scope pictures and notice the voltage of the pulses goes over and under 0.6 volts )
If you were lucky and had an abs model cb1100 there is a possibility to use the pink/green wire that runs between the abs unit and the instrument cluster, which carries a higher level ( 0 to 5 volt with respect to ground hence ONE wire, i think ) pulse signal that uses a separate input on the cluster specifically for the abs signal which the power commander unit " understands".
What essentially happens; inside a digital ( 0 to 5 volts ) input is a transistor.
transistors start conducting ( switching on ) above 0.6 volts, so the input senses a 0 volt input and sees this as a "low" signal,
as soon as the transistor sees more than 0,6 volt it switches "on"and tells the processor it has a "high" signal,
the tempo that it sees low to high pulses determines how much the processor drives the speedometer.
This video shows the pcv connected to the gear speed sensor at the ecm ;
So our speed sensor uses an entirely different input circuit and can possibly be damaged by applying external voltages to either of the two input wires, what is pherhaps not realized is that in the course of things we learned over the years i made many mistakes that broke a lot of equipment in the process, we don't want to cause this to anybody else and warn them if we can see a potential problem on the horizon which may not be obvious to them.
I suspect you knew some of this already but i thought i would tell the whole story for everyone's benefit and in addition to popgun's advice.
, sorry guys
