Multiple sensor returns on same wire

Question

How does a PCM (Powertrain Control Module), a.k.a. ECM, know which sensor is which when multiple sensors' return signal is on the same wire? I have a 2004 F150 wiring diagrams manual and am perplexed to see that the signal return from multiple sensors are spliced together on the same wire back to the PCM. If a sensor has an open circuit, how does the PCM know which sensor? What if two sensors on the same wire have an open circuit?

Will appreciate your help to understand this.

4/19 Reply [If this is not the right way to reply please let me know.]

Thanks you for the information. It very clearly answers my questions, and I really appreciate learning how this works.

I haven't looked at he wiring diagram for your vehicle, so this could be wrong, but it is one possibility. Can you add a section of the wiring diagram?

FYI here is one page showing multiple sensors on the same return wire.

And thanks again for your help.

Answer 1

The information being passed along the wire will be digital, much the same as the way your internet connection to your house has data from lots of locations being passed along it at the same time.

The data will be transferred as packets, each containing the sensor data along with data identifying which sensor is sending it.

If a sensor goes open circuit, then the PCM will realise that it hasn't received any data packets with the ID for that sensor.

I haven't looked at he wiring diagram for your vehicle, so this could be wrong, but it is one possibility. Can you add a section of the wiring diagram?