Signal not being picked up

[igna92ts]

Im trying to hook up my rowing machine sensors but im having trouble getting to pick up the signal. Now this may be entirely my fault (and probably is) My problem is I don't quite understand how the sensors on my machine would work. The connection to where im assuming the sensors are looks like this

and the cables coming out of it that go into the monitor that came with the machine look like this So two cables go into each, what it looks like, a headphone plug and jack? My understanding of electronics and electrics is almost none so I don't get how this would work as the library just expects a connection on gpio 17 but I would have 4 cables total coming out of the thing so im guessing 2 ground and 2 signals?.

What I tried is hooking it up with something like this And the one of those to gpio 17 and the other to GND.

Sorry for the ignorance so feel free to close the issue if it's too much to answer.