Hi Systemsc

To start with thank you for your help
I’m exposing my lack of knowledge on the subject, but regarding your response on LINK,, did I understand correctly that two different signals run on the same cable, one of which reaches its destination while the other does not?
I’m trying to understand if it makes sense to continue troubleshooting the cables or not.
What makes the signal go through when I plug in a simple OBD reader?(As the car then cranks and starts) I’ve interpreted it as having some kind of resistance in the OBD reader is enough to get the car to start.

Thank you